# CVE-2026-86805: GNU C Library dynamic loader privilege escalation via TOCTOU race

Source: https://junglewise.ai/threats/cve-2026-86805-a-time-of-check-to-time-of-use-toctou-race-condition-in-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-22. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-86805 · Severity: medium · CVSS 6.3 · Published 2026-09-22

A flaw in the GNU C Library's dynamic loader allows local attackers to execute arbitrary code with elevated privileges on systems with a specific kernel setting disabled. When a setuid or setgid program uses certain library search paths, an attacker can exploit a timing gap to inject a malicious library that gets loaded and executed with the program's elevated rights, leading to privilege escalation.

Technologies: [Gnu C Library (glibc)](https://junglewise.ai/threats/technologies/c-library-glibc). Vendors: [Gnu](https://junglewise.ai/threats/vendors/gnu).

## Quick answers

**Is CVE-2026-86805 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86805 being exploited in the wild.

**How severe is CVE-2026-86805?** Medium severity, with a CVSS score of 6.3, published 22 September 2026.

**Which products and versions are affected?** Gnu C Library (glibc) 2.14 through 2.44.

**Is there a fix for CVE-2026-86805?** A patch was published on 2026: Fix included in glibc 2.45 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86805 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-86805?** Check whether you run Gnu C Library (glibc) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A TOCTOU race condition in glibc's ld.so during $ORIGIN expansion in DT_RPATH for AT_SECURE processes allows local privilege escalation. The loader validates the normalized path against trusted directories but opens the raw, un-normalized path, permitting traversal sequences like "/tmp/a/b/../../../usr/lib". On systems with fs.protected_hardlinks disabled, an attacker can hard-link the setuid/setgid binary and race to replace path components with symlinks, redirecting the loader to load attacker-controlled shared objects.

## Affected products

- GNU C Library (glibc) 2.14 through 2.44

## Timeline

- 2026-07-06: disclosed
- 2026: patched: Fix included in glibc 2.45

## References

- [https://sourceware.org/bugzilla/show_bug.cgi?id=34360](https://sourceware.org/bugzilla/show_bug.cgi?id=34360)
- [https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022](https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022)

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