CVE-2026-86805 (GCVE-0-2026-86805)

Vulnerability from cvelistv5 – Published: 2026-09-22 15:55 – Updated: 2026-09-23 03:55
VLAI
Title
AT_SECURE programs may load attacker-controlled code via $ORIGIN
Summary
A time-of-check to time-of-use (TOCTOU) race condition in the dynamic loader (ld.so) of the GNU C Library (glibc) versions 2.14 through 2.44 allows a local attacker to escalate privileges. When expanding $ORIGIN in DT_RPATH for setuid/setgid (AT_SECURE) programs, glibc validates the lexically normalized search path against the trusted directories but then opens the raw, un-normalized path. On systems where the Linux fs.protected_hardlinks sysctl is disabled, a local attacker who hard-links such a program into an attacker-controlled directory and wins a race to replace an intermediate path component with a symbolic link can direct the loader outside the trusted directory, causing it to load an attacker-controlled shared object and execute arbitrary code with the elevated privileges of the program. Exploitation requires an installed setuid or setgid binary whose DT_RPATH uses $ORIGIN followed by ".." traversal that normalizes into a trusted directory, and the ability to hard-link that binary and win the race by swapping a path component for a symbolic link. Major Linux-based OS distributions ship with fs.protected_hardlinks enabled by default and mitigate the vulnerability.
Severity
6.3 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-22 00:00 UTC
CWE
  • CWE-367 - Time-of-check time-of-use (TOCTOU) race condition
Assigner
glibc CNA under the redhat root
CNA scorecard B 80/100 over 12 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
The GNU C Library glibc Affected: 2.14 , < 2.45 (custom)
guessed Create a notification for this product.
Credits
Jann Horn
Show details on NVD website
To clipboard 

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