Vulnerability in Linux kernel (CVE-2026-89836)
Summary
Vulnerability in Linux kernel (CVE-2026-89836). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix folio_nr_pages() race after put in large folio invalidate
Our v6.18 based Android system is continuely suffering livelock and bad
page stat as shown in[1] which related to broken xarray slot status. By
investigating big folio operations within f2fs, we find below races and
fix it by get the nr_pages before drop the refcount and folio_lock.
f2fs_get_read_data_folio() calls f2fs_folio_put() before
folio_nr_pages() when invalidating a large folio from the page cache.
That unlocks the folio and drops the caller reference, leaving a window
where a concurrent truncate or folio split can shrink the compound folio
or free it before the invalidate range is computed. An undersized range
then leaves split sub-folios in mapping->i_pages, which can later
interact badly with truncate and reclaim (stale xarray entries and bad
page state when folio->mapping no longer matches the mapping being
truncated).
[1]
PID: 2594 TASK: ffffff8169b81580 CPU: 7 COMMAND: "Thread-3"
#0 [ffffffc08ef2b8a0] xas_load at ffffffe52d1f42a4
#1 [ffffffc08ef2b900] find_get_entries at ffffffe52c185798
#2 [ffffffc08ef2bb60] truncate_inode_pages_range at ffffffe52c19e83c
#3 [ffffffc08ef2bbc0] truncate_inode_pages_final at ffffffe52c19ec2c
#4 [ffffffc08ef2bc20] f2fs_evict_inode at ffffffe52c4c8400
#5 [ffffffc08ef2bcc0] evict at ffffffe52c2de9f4
#6 [ffffffc08ef2bd00] iput at ffffffe52c2db1b4
#7 [ffffffc08ef2bd30] dentry_unlin…
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-2026-89836 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89836" on the vendor's site.
CVE-2026-89836 (Linux kernel) — CVSS v3 7.8
Attack vector: local / no user interaction
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: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.
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-2026-89836 linux Fixed in: 7.2.6-1
- Ubuntu UBUNTU-CVE-2026-89836 linux-hwe-edge
References
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com