CVE-2026-74620

CVE CVE-2026-74620EUVD EUVD-2026-64557Veröffentlicht 2026-08-22T15:32:04.000ZZuletzt geändert 2026-08-23T12:47:46.000Z

Was das Advisory beschreibt

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_gact, act_police: range check the fallback control action tcf_action_check_ctrlact() range checks the primary control action: if (!opcode) ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0; TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it cannot be set that way. But act_gact and act_police each carry a second, independent control action supplied by user space that never reaches that helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned verbatim from the action. In particular user space can store TC_ACT_CONSUMED, which is TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value range. That verdict tells every caller the action took ownership of the skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for it. The result is one leaked sk_buff plus its data buffer per packet traversing the filter, unbounded, for all traffic on the chain including kernel-generated packets. Both are trivially deterministic. act_gact clamps tcfg_pval to >= 1, so with pval = 1 gact_determ() returns the fallback for every packet. act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and tcf_police_mtu_check() always passes. TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor reinsert action"), after both goto-chain guards were written: commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on fallback control action") and commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on fallback control action"). Neither guard was widened when the new verdict appeared. Factor the existing range test out of tcf_action_check_ctrlact() as tcf_action_valid() and apply it to both fallbacks. The helper cannot call tcf_action_check_ctrlact() directly because that also allocates a goto_chain, which is exactly what these two sites must not do. Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet. With this patch both configurations are rejected with -EINVAL and kmemleak 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 patch: 6.18.45; patch: 7.1.9; 720f22fed81bc6fd1765db7014651b6718887bea <5f038affdacaffedf6a85a06cf59ec0a852d36a7; 720f22fed81bc6fd1765db7014651b6718887bea <92f00f1d4d204a428b38e26fce3baee144b6955d; 5.3; 720f22fed81bc6fd1765db7014651b6718887bea <883b56ae58fe657d8497806c7059646e9ba6dbd0; 720f22fed81bc6fd1765db7014651b6718887bea <5344e01179baa37547ab29fd7b8614f83faa190c; patch: 0; patch: 6.1.183; patch: 5.10.266; patch: 5.15.216; 720f22fed81bc6fd1765db7014651b6718887bea <efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4; 720f22fed81bc6fd1765db7014651b6718887bea <725efc2ab4a40affc4e285a2dc4896d103948a6c; 720f22fed81bc6fd1765db7014651b6718887bea <6bcb8839aa2d686964a4154650afc4db91e1c514; patch: 6.12.104; patch: 6.6.152; patch: 7.2; 720f22fed81bc6fd1765db7014651b6718887bea <2e8df8c9190335475a3b64a159d3efd8cdd1cb73

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.