CVE-2026-86805

Description

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.

Overview

State: PUBLISHED
Assigner (CNA): glibc
CVSS severity: MEDIUM
CVSS score: 6.3 / 10
CVSS vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
Effective score: 6.3 / 10 MEDIUM source: CNA overview
MSRC score: 6.3 / 10 MEDIUM MS rating: Moderate
CWE(s): CWE-367
Reserved: 2026-09-08
Published: 2026-09-22 15:55 UTC
Last updated: 2026-09-22 16:42 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/86xxx/CVE-2026-86805.json

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-09-22 16:18:06 UTC
NVD last modified: 2026-09-22 19:56:19 UTC
NVD CVSS v3.1: 6.3 / 10 MEDIUM source: 3ff69d7a-14f2-4f67-a097-88dee7810d18
NVD CVSS vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
Exploitability subscore: 0.8 / 10
Impact subscore: 5.5 / 10

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-84540
Assigner: glibc
Published: Sep 22, 2026, 3:55:17 PM
Updated: Sep 23, 2026, 3:55:58 AM
EUVD base score (CVSS 3.1): 6.3 / 10
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
EUVD-reported EPSS: 0.0000
Vendors: The GNU C Library
Products: glibc (2.14 <2.45)
Aliases: GHSA-fmf4-pr35-46c2

ENISA description: 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.

EUVD references (2)

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-09-26 03:08 UTC (source: CVRF).

MS severity: Moderate
MS CVSS base score: 6.3 / 10 (temporal 6.3)
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
Release: 2026-Sep

Microsoft remediations / KB articles (2)

Release Notes — Vendor Fix / Security Update
https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade — None Available / Release Notes

Affected products (1)

Vendor	Product	Versions	Platforms
The GNU C Library	glibc	`2.14` (affected)	—

Vendor references (2)

References embedded in the original CVE record by the assigning CNA.

https://sourceware.org/bugzilla/show_bug.cgi?id=34360 issue-tracking
https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022 vendor-advisory

Web references (2)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

None Available msrc
MSRC update guide: CVE-2026-86805 msrc

NVD-tagged references (2)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://sourceware.org/bugzilla/show_bug.cgi?id=34360 3ff69d7a-14f2-4f67-a097-88dee7810d18
https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022 3ff69d7a-14f2-4f67-a097-88dee7810d18

Remediations (10)

September 2026 Patch Breaks RDS: Fix Without Rolling Back

web:byteiota.com

That's not all. September's Patch Tuesday also fixed two zero-days under active exploitation: CVE - 2026 -85880, a heap buffer overflow in Windows ALPC that allows local privilege escalation to SYSTEM, and CVE - 2026 -81963, a link-following flaw in the Windows Update Stack. Rolling back removes those fixes too.

2026-09-23 15:42 UTC
Security Update Guide - Microsoft

web:msrc.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-09-23 15:42 UTC
Out-of-band Security Notification (September 2, 2026)

web:my.f5.com

On September 2, 2026 , F5 announced the following security issues. This document is intended to serve as an index of these vulnerabilities and security exposures to help determine the impact to your F5 devices. You can find the details of each issue in the associated articles.

2026-09-23 15:42 UTC
Cisco Advance Notification for Publication of September 16, 2026 ...

web:sec.cloudapps.cisco.com

On September 16, 2026 , the Cisco Product Security Incident Response Team (PSIRT) published the advisories that are listed in the following tables. To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the ...

2026-09-23 15:42 UTC
Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-09-23 15:42 UTC
Description of the security update for Office 2016: August 11, 2026 ...

web:support.microsoft.com

Be aware that the update in the Microsoft Download Center applies to the Microsoft Installer (.msi)-based edition of Office 2016. It doesn't apply to the Office 2016 Click-to-Run editions, such as Microsoft Office 365 Home. (See What version of Office am I using?) How to get and install the update Method 1: Microsoft Update This update is available from Microsoft Update. When you turn on ...

2026-09-23 15:42 UTC
CVE-2026-6875 - Sandbox Escape in ServiceNow AI Platform

web:support.servicenow.com

ServiceNow has addressed a critical remote code execution vulnerability that was identified in the ServiceNow AI platform. This vulnerability, tracked as CVE - 2026 -6875, could enable an unauthenticated user, in certain circumstances, to execute code within the ServiceNow platform. Resolution

2026-09-23 15:42 UTC
August 2026 CVE Advisory Notification - Security

web:support.servicenow.com

Due to additional analysis provided by the security researcher who discovered CVE - 2026 -6876, we have upgraded the severity rating of CVE - 2026 -6876 from High to Critical. This change affects only the severity

2026-09-23 15:42 UTC
Multiple Vulnerabilities in Google Chrome Could Allow for Arbitrary ...

web:www.cisecurity.org

Multiple vulnerabilities have been discovered in Google Chrome, the most severe of which could allow for arbitrary code execution. Successful exploitation of the most severe of these vulnerabilities could allow for arbitrary code execution in the context of the logged on user. Depending on the privileges associated with the user an attacker could then install programs; view, change, or delete ...

2026-09-23 15:42 UTC
Patch Tuesday September 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's September 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-09-23 15:42 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-86805.json.

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