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.
References
Configurations
No configuration.
History
22 Sep 2026, 17:17
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 6.3 |
22 Sep 2026, 16:18
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-09-22 16:18
Updated : 2026-09-23 04:17
NVD link : CVE-2026-86805
Mitre link : CVE-2026-86805
CVE.ORG link : CVE-2026-86805
JSON object : View
Products Affected
No product.
CWE
CWE-367
Time-of-check Time-of-use (TOCTOU) Race Condition