Vulnerability in Linux kernel (CVE-2026-90109)
Summary
Vulnerability in Linux kernel (CVE-2026-90109). 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:
net: sched: fix 32-bit backlog wrap in gred, bfifo and plug enqueue
gred_enqueue(), bfifo_enqueue() and plug_enqueue() admit a packet when the
current backlog plus the packet length fits within the queue limit:
sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (gred default VQ)
gred_backlog+qdisc_pkt_len(skb) <= q->limit (gred configured VQ)
sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (bfifo)
sch->qstats.backlog + skb->len <= q->limit (plug)
sch->qstats.backlog and q->backlog are u32, and qdisc_pkt_len()/skb->len
are unsigned int, so all sums are computed in 32 bits and wrap at 2^32.
Once the true backlog exceeds 4 GiB the wrapped sum becomes small and
admission keeps succeeding, so the queue grows without bound and the kernel
can be driven to OOM.
Promote the sums to u64 so admission stops once the true backlog exceeds
the limit. The limit is u32, so the bounded queue stays below 2^32 and
the stored u32 backlog never wraps.
The bug can only be reproduced as root (albeit with ridiculous setup):
attach a gred (or bfifo/plug) qdisc with a limit near 4 GiB,
leaving the default VQ unconfigured (for gred), and drive >4 GiB of
queued traffic (e.g. via a size table / stab to inflate qdisc_pkt_len,
or sustained high-rate traffic). The u32 backlog+len sum wraps at 2^32,
admission keeps succeeding, and the queue grows unboundedly to OOM.
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-2026-90109 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-2026-90109" on the vendor's site.
CVE-2026-90109 (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 git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com