AT_SECURE programs may load attacker-controlled code via $ORIGIN

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-86805
StatePUBLISHED
Assignerglibc
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 16:18:06 UTC
Updated2026-09-23 04:17:57 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.1 6.3 MEDIUM from 3ff69d7a-14f2-4f67-a097-88dee7810d18

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L

EPSS: 0.001240000 probability, percentile 0.024700000 (date 2026-09-23)

Problem Types: CWE-367 | CWE-367 CWE-367 Time-of-check time-of-use (TOCTOU) race condition

VersionSourceTypeScoreSeverityVector
3.13ff69d7a-14f2-4f67-a097-88dee7810d18Secondary6.3MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
3.1CNACVSS6.3MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
Low

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA The GNU C Library Glibc affected 2.14 2.45 custom Not specified

References

ReferenceSourceLinkTags
sourceware.org/bugzilla/show_bug.cgi 3ff69d7a-14f2-4f67-a097-88dee7810d18 sourceware.org
sourceware.org/git 3ff69d7a-14f2-4f67-a097-88dee7810d18 sourceware.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Jann Horn (en)

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