Vulnerability in Linux kernel (CVE-2026-90261)
Summary
Vulnerability in Linux kernel (CVE-2026-90261). 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: zoned: flush active metadata block group at btree_writepages() start
btree_writepages() writes the btree inode's dirty metadata in ascending
logical address order. On a zoned filesystem only one metadata and one
system block group is active for writing at a time, and
check_bg_is_active() (via btrfs_check_meta_write_pointer()) pivots the
active block group as writeback moves from one block group to the next.
If the active block group sits at a higher logical address than another
block group that also holds dirty metadata, the ascending walk reaches
the lower one first and, to write it, has to finish the active block
group and activate the lower one. It cannot finish a block group that
still has unsent IO, and during WB_SYNC_ALL && !for_sync (commit)
writeback it deliberately refuses to wait for that IO under
fs_info->zoned_meta_io_lock, as that can deadlock. The pivot thus cannot
issue the submission itself either, so it gives up:
btrfs_check_meta_write_pointer() returns -EAGAIN, which
btrfs_write_and_wait_transaction() treats as fatal and aborts the
transaction, forcing the filesystem read-only. This happens
intermittently under metadata-heavy relocation (e.g. fstests btrfs/187).
Flush the active metadata and system block groups at the start of
btree_writepages(), under the fs_info->zoned_meta_io_lock it already
holds, so they have no unsent IO left and the later pivot can finish
them and make forw…
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-2026-90261 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-2026-90261" on the vendor's site.
CVE-2026-90261 (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。
References
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com
- web git.kernel.org