CVE-2026-74621

CVE CVE-2026-74621EUVD EUVD-2026-64558Veröffentlicht 2026-08-22T15:32:04.000ZZuletzt geändert 2026-08-25T05:40:45.000ZCVSS 7.5

Was das Advisory beschreibt

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: fix sk_buff leak when the header checks reject a packet tcf_ct_handle_fragments() runs its header sanity checks before handing anything to the defragmentation engine: if (family == NFPROTO_IPV4) err = tcf_ct_ipv4_is_fragment(skb, &frag); else err = tcf_ct_ipv6_is_fragment(skb, &frag); if (err || !frag) return err; tcf_ct_ipv4_is_fragment() returns -EINVAL or -ENOMEM; tcf_ct_ipv6_is_fragment() adds -EPROTO when ipv6_find_hdr() fails. None of them frees or queues the skb, so on that path the caller still owns it. tcf_ct_act() however funnels every non-zero return into the ownership-transfer exit: err = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag); if (err) goto out_frag; ... out_frag: if (err != -EINPROGRESS) tcf_action_inc_drop_qstats(&c->common); return TC_ACT_CONSUMED; TC_ACT_CONSUMED means the action took ownership of the skb, so no caller frees it - sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for that verdict. The skb is therefore orphaned: one sk_buff plus its data buffer is leaked per malformed packet, unbounded. Note the drop counter is already incremented for these errors, so the statistics claim a drop that never happens. Three different ownership states reach out_frag: today - the skb may be queued by the defrag engine (-EINPROGRESS), already freed by nf_ct_handle_fragments(), or still owned by us. Tell the caller which of those it is, and free the packet ourselves in the last case, which restores the TC_ACT_SHOT behaviour that predated the Fixes: commit. Reproduced on v7.2-rc6 with a 54-byte frame carrying a 40-byte IPv6 header with nexthdr = 0 (hop-by-hop) and nothing after it, on a clsact ingress chain with "action ct". kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet; with this patch it reports none.

Quelle: EUVD (ENISA), im Wortlaut der Meldung.

Produkte, die das Advisory nennt

Diese Angaben stammen aus der Meldung selbst, nicht aus einer Prüfung durch uns.

• Linux — Linux 3f14b377d01d8357eba032b4cabc8c1149b458b6 <b47bb899e04b5407c5a63fe88d4b6676586a6e84; patch: 7.1.9; patch: 6.12.104; patch: 7.2; 3f14b377d01d8357eba032b4cabc8c1149b458b6 <439d3e404f9d5e515911cc8132cde198b337c19e; 73f7da5fd124f2cda9161e2e46114915e6e82e97 <737873a59905a54ca0d2d127ef882f3f88bf4379; patch: 6.1.184; 6.1.75 <6.1.184; patch: 6.6.152; 6.6.14 <6.6.152; 172ba7d46c202e679f3ccb10264c67416aaeb1c4 <b5dbecc2016e1692fd1c2532af9c41ba729cb747; 5.15.148 <5.15.217; 3f14b377d01d8357eba032b4cabc8c1149b458b6 <8a7ed561671aa6a911a2de99e59ef670a4d0b1df; patch: 0; patch: 5.15.217; 3f14b377d01d8357eba032b4cabc8c1149b458b6 <47d99828591d0fe8be4b9c8992ff3b8e47968db9; f5346df0591d10bc948761ca854b1fae6d2ef441; 6.7.2 <6.8; 6.8; patch: 6.18.45; 0b5b831122fc3789fff75be433ba3e4dd7b779d4 <23e97d594ddd0153020c506d5041048fbde1beb4

Die genannten Versionen sind die Angabe der Meldung. Patchlage vergleicht keine Versionsnummern und leitet aus ihnen keine Aussage ab — welche Version installiert ist, muss ein Mensch nachsehen.

Im Produktkatalog geführt

Für diese Produkte kann ein Bestand in Patchlage erfasst werden. Ein Advisory dazu erscheint am Morgen danach im Lagebericht.

• Linux — Linux

Patchlage meldet Treffer und Verdachtsfälle. Zu allem anderen sagt dieses System nichts — weder diese Seite noch der Lagebericht behauptet je, dass ein Bestand sicher ist.