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Linux CVE-2026-90263

| EUVDEUVD-2026-81856
2026-09-17 Linux GHSA-wxw8-hpqh-3xg2
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Monitor Track and reassess. Why: No CVSS yet + weak signal (CWE or non-zero EPSS).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisCVE.org

In the Linux kernel, the following vulnerability has been resolved:

btrfs: check if root is readonly when setting posix acl

For a filesystem which has btrfs read-only property set to true, all write operations including acl and xattr should be denied. However, acl can still be set even if btrfs ro property is true.

This happens because no function on the set_acl code path checks the root is readonly or not. It was checked in btrfs_setxattr_trans() but got removed in commit 353c2ea735e4 ("btrfs: remove redundant readonly root check in btrfs_setxattr_trans")

That commit didn't check if all the callers properly check the root's read-only flag. A previous fix is commit b51111271b03 ("btrfs: check if root is readonly while setting security xattr").

Always check if the root is read-only before performing the set acl operation.

Affected VersionsENISA

Linux patch: 7.2.6
Linux 353c2ea735e4b54fb6250861e67b51b1bcb47198 <01c2f41fc441f75b3f9326443372faceb1cb6638
Linux patch: 0
Linux 5.2
Linux 353c2ea735e4b54fb6250861e67b51b1bcb47198 <d5602f96ff1e266f069b4d0d94f441050e057e06
Linux patch: 7.3-rc1

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Lifecycle Timeline

2
Patch available
Sep 17, 2026 - 17:19 EUVD
CVE Published
Sep 17, 2026 - 16:08 cve.org
UNKNOWN (no severity yet)

Threat Intelligence Overview

EPSS Score
0.2%
Top 91% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity Not scored yet
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
No CVSS yet + weak signal (CWE or non-zero EPSS)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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