CVE-2026-90109net: sched: fix 32-bit backlog wrap in gred, bfifo and plug enqueue
- —Not scoredno CVSS score yet
- 0.23%Exploitation in 30 daysEPSS · top 86% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 6 days later
· 6 days later
Published
- 43 days later
· 43 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.23% · top 86% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 – < 771a1123570b487765bcf2d4cff3567e66bf1322
- affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 – < c5ca77024812563fe15c4f7aa906791c3683e9fd
- affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 – < 3fb51b3960342bbee563543f8d33710fd0fb5a96
- affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 – < 8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6
- affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 – < d98b92f3d57976ae185238946ec5ea0be32195aa
- affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 – < 4c660ee8c809637909f4f7eb1017f7b9401c75c4
- affected 4.2
- unaffected < 4.2
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.160 – ≤ 6.6.*
- unaffected 6.12.110 – ≤ 6.12.*
- unaffected 6.18.52 – ≤ 6.18.*
- unaffected 7.2.6 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References6
- https://git.kernel.org/stable/c/771a1123570b487765bcf2d4cff3567e66bf1322 (opens in a new tab)
- https://git.kernel.org/stable/c/c5ca77024812563fe15c4f7aa906791c3683e9fd (opens in a new tab)
- https://git.kernel.org/stable/c/3fb51b3960342bbee563543f8d33710fd0fb5a96 (opens in a new tab)
- https://git.kernel.org/stable/c/8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6 (opens in a new tab)
- https://git.kernel.org/stable/c/d98b92f3d57976ae185238946ec5ea0be32195aa (opens in a new tab)
- https://git.kernel.org/stable/c/4c660ee8c809637909f4f7eb1017f7b9401c75c4 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-81702 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-90109)Record last updated .