Vulnerability in Linux

[ Description ]Official description

In the Linux kernel, the following vulnerability has been resolved: net/sched: drr: clamp quantum in change class drr_change_class() rejects explicit quantum==0 but falls back to psched_mtu() with no floor. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 (or a zero psched_mtu on a headerless device) makes the deficit-refill loop spin under the qdisc lock. Add clamp_t(u32, quantum, 256, 1<<20) after the zero reject and on the fallback path. The explicit-zero reject is preserved. Conditions to recreate the bug: CONFIG_NET_SCH_DRR=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root drr tc class add dev dummy0 parent 1: classid 1:1 drr quantum 1

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• CERT-FR9 Oct 2026CERTFR-2026-AVI-1289

  Multiple vulnerabilities in the Debian LTS Linux kernel Translated from French

  Multiple vulnerabilities have been discovered in the Debian LTS Linux kernel. Some of them allow an attacker to cause privilege escalation, a breach of data confidentiality and denial of service.

  CVE-2025-38237CVE-2025-39833CVE-2025-39925+1311 more CVEs
• CERT-FR2 Oct 2026CERTFR-2026-AVI-1253

  Multiple vulnerabilities in the Debian Linux kernel Translated from French

  Multiple vulnerabilities have been discovered in the Debian Linux kernel. Some of them allow an attacker to cause privilege escalation, a breach of data confidentiality and denial of service.

  CVE-2025-38237CVE-2025-39833CVE-2025-39925+1310 more CVEs
• BSI CERT-Bund24 Sep 2026WID-SEC-2026-3579

  Linux Kernel: Multiple vulnerabilities Translated from German

  CVE-2026-97615CVE-2026-97978CVE-2026-98127+590 more CVEs

[ References ]References

• git.kernel.org/stable/c/23fea7e6736b2e1c6f6f2f05cccf33d36834da73
• git.kernel.org/stable/c/560794ee6e040b6e1c4ac2b3c8909f341a4596ee
• git.kernel.org/stable/c/8382abec0f1568d0a5590d75a3df92f23fcf5196
• git.kernel.org/stable/c/8f756ae1c87414ce9cc21b30e6e4c036d6e9e80b
• git.kernel.org/stable/c/b464affe9f9dfe41ac48930c376e3fb8596651b0
• git.kernel.org/stable/c/d43cded350fe1218493ad3d37a276aff14108ae6
• git.kernel.org/stable/c/dc8b374214ef5bba4882bbd95b361e42555cfc0d
• git.kernel.org/stable/c/e2297bbf9cf6ece86f1d1f8c683517a994990f9e