Vulnerability in Linux kernel (CVE-2026-89772)
Summary
Vulnerability in Linux kernel (CVE-2026-89772). 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: write-protect folios during data writeback
commit 095be159f3eb ("btrfs: unify folio dirty flag clearing") replaced
the folio_clear_dirty_for_io() call in extent_write_cache_pages() with a
plain folio_test_dirty() check. Besides clearing the dirty flag,
folio_clear_dirty_for_io() also calls folio_mkclean(), which write-protects
the shared mmap PTEs mapping the folio. Note that we still do call
folio_clear_dirty_for_io() later in submit_one_sector() when we clear
dirty on the last sector of the folio (the only sector for non-subpage
cases). But we lost this early call in extent_write_cache_pages().
Without the extra write-protection, a process with the file mmap-ed can
modify a sector while it is being used by writeback in a way that
expects a stable folio (checksumming, compressing, copying, etc...)
without faulting, which manifests as a handful of concrete bugs.
- For large folios or subpage sectorsize, it is possible to submit a bio
which does not cover the whole folio. When this happens, we will have a
bio in flight for a folio that we have not called
folio_clear_dirty_for_io() on. If a task with an existing mmap-ed PTE
writes (without faulting..) in this window, it can result in
corruptions. If the write arrives while the checksumming or writing itself
is underway, this can result in an invalid checksum and later corruption
reports on read. If the write arrives after checksumming/writing is d…
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-2026-89772 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-2026-89772" on the vendor's site.
CVE-2026-89772 (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。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-89772 linux Fixed in: 7.2.6-1
- Ubuntu UBUNTU-CVE-2026-89772 linux-hwe-edge
References
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com