Vulnerability in Linux

[ Description ]Official description

In the Linux kernel, the following vulnerability has been resolved: net: reject oversized tx_queue_len at netlink parse time rtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len without going through netif_change_tx_queue_len(), so a device created with "ip link add ... txqueuelen 500000" bypasses the S16_MAX cap and still triggers the oversized ring allocations in pfifo_fast, tun and tap. The veth peer nest (rtnl_nla_parse_ifinfomsg()) and the RTM_NEWLINK-on-existing-device path reach the same sinks. Enforce the cap in ifla_policy instead: IFLA_TXQLEN becomes NLA_POLICY_FULL_RANGE(NLA_U32, &txqlen_range) with txqlen_range = { .min = 0, .max = S16_MAX }. All netlink consumers parse against this policy - rtnl_setlink(), rtnl_newlink() (create and change), and the veth peer nest - so every netlink path is capped at parse time and rejects the attribute with -ERANGE plus a proper "integer out of range" extack message before any device state is modified (the RTM_SETLINK half-application wart is gone with it). Document the bound in the rt-link.yaml netlink spec. Conditions to recreate the bug: - CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y. - Unprivileged user in a fresh user+net namespace (unshare -Urn): ip link add v0 txqueuelen 500000 type veth peer name v1 -> on the fixed kernel this is rejected with -ERANGE ("integer out of range" extack) instead of installing an oversized tx_queue_len that later inflates pfifo_fast/tun/tap ring allocations. - ip link set v0 txqueuelen 500000 is likewise rejected at parse time.

[ 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/1aa9e143bf51405665a793d4cc925e1c4f0c5922
• git.kernel.org/stable/c/26ee5f99ffe7ab98e635071290eff14192e9e34a
• git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38
• git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34
• git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b