Vulnerability in Linux kernel (CVE-2026-90263)
Summary
Vulnerability in Linux kernel (CVE-2026-90263). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-90263 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-90263" on the vendor's site.
CVE-2026-90263 (Linux kernel)
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-90263 linux-lts
- Debian DEBIAN-CVE-2026-90263 linux
- Ubuntu UBUNTU-CVE-2026-90263 linux-hwe-edge
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com
- web git.kernel.org