Vulnerability-Lookup

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

Vulnerability from cvelistv5 – Published: 2026-09-22 15:55 – Updated: 2026-09-23 03:55

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 redhat root

References

2 references

URL	Tags
https://sourceware.org/bugzilla/show_bug.cgi?id=34360	issue-tracking
https://sourceware.org/git/?p=glibc.git;a=blob_pl…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
The GNU C Library	glibc	Affected: 2.14 , < 2.45 (custom)	guessed

Credits

Jann Horn

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-86805

Vulnerability from fkie_nvd - Published: 2026-09-22 16:18 - Updated: 2026-09-23 04:17

Severity

6.3 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L

Summary

References

	URL	Tags
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	3ff69d7a-14f2-4f67-a097-88dee7810d18	https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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GHSA-FMF4-PR35-46C2

Vulnerability from github – Published: 2026-09-22 18:33 – Updated: 2026-09-22 18:33

Details

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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-86805"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-22T16:18:06Z",
    "severity": "MODERATE"
  },
  "details": "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.\n\nExploitation 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.",
  "id": "GHSA-fmf4-pr35-46c2",
  "modified": "2026-09-22T18:33:29Z",
  "published": "2026-09-22T18:33:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86805"
    },
    {
      "type": "WEB",
      "url": "https://sourceware.org/bugzilla/show_bug.cgi?id=34360"
    },
    {
      "type": "WEB",
      "url": "https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

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

FKIE_CVE-2026-86805

GHSA-FMF4-PR35-46C2

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