CVE-2026-72123

CVE CVE-2026-72123EUVD EUVD-2026-58881Veröffentlicht 2026-08-15T05:53:01.000ZZuletzt geändert 2026-08-19T16:36:18.000ZCVSS 7.8

Was das Advisory beschreibt

In the Linux kernel, the following vulnerability has been resolved: can: bcm: defer rx_op deallocation to workqueue to fix thrtimer UAF Commit f1b4e32aca08 ("can: bcm: use call_rcu() instead of costly synchronize_rcu()") replaced synchronize_rcu() in bcm_delete_rx_op() with call_rcu() and introduced the RX_NO_AUTOTIMER flag. However, this flag check was omitted for thrtimer in the packet rx fast-path. During BCM RX operation teardown, a concurrent RCU reader (bcm_rx_handler) can race and re-arm thrtimer via bcm_rx_update_and_send() after call_rcu() has been scheduled. Once the RCU grace period elapses, bcm_op is freed. The subsequently firing thrtimer then dereferences the deallocated op, causing a UAF. Adding flag checks to the rx fast-path (bcm_rx_update_and_send) does not fully close the TOCTOU race and introduces latency for every CAN frame. Conversely, calling hrtimer_cancel() directly inside the RCU callback (softirq context) is fatal as hrtimer_cancel() can sleep, triggering a "scheduling while atomic" panic. Resolve this by deferring the timer cancellation and memory free to a dedicated unbound workqueue (bcm_wq). The RCU callback now queues a work item to bcm_wq, which safely cancels both timers and deallocates memory in sleepable process context. A dedicated workqueue is used to prevent system-wide WQ saturation and is cleanly flushed/destroyed on module unload to avoid rmmod page faults. Since the deferred work can now outlive the calling context by an unbounded amount, also take a reference on op->sk when it is assigned and drop it only once the deferred work has cancelled both timers, so a socket can no longer be freed out from under a still-armed timer whose callback (bcm_send_to_user()) dereferences op->sk.

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: 6.18.40; f1b4e32aca0811aa011c76e5d6cf2fa19224b386 <cd830e0bc25ee2d38cbfbdbb3cd77c5f53b2b6d5; 4.19.252 <4.20; edb4baffb9483141a50fb7f7146cfe4a4c0c2db8; f34f2a18e47b73e48f90a757e1f4aaa8c7d665a1 <036a8c320ca11bc912e8027adcfad14b326f067e; 5.10.130 <5.10.265; patch: 7.1.5; patch: 5.15.216; f1b4e32aca0811aa011c76e5d6cf2fa19224b386 <68973f9db76144825e4f35dfdc80fb8279eb2d57; 5.4.205 <5.5; fbac09a3b8890003c0c55294c00709f3ae5501bb; f1b4e32aca0811aa011c76e5d6cf2fa19224b386 <4177762f70646ac48a2af382e45a795cbd295198; f1b4e32aca0811aa011c76e5d6cf2fa19224b386 <6fd08e8d826c3aa4cc7021f5f9cdbb7fa7441d3f; patch: 0; 5.19; patch: 6.6.145; 85cd41070df992d3c0dfd828866fdd243d3b774a <de5fce46637de05bef56ec08528127676eb6fc9b; patch: 6.12.97; f1b4e32aca0811aa011c76e5d6cf2fa19224b386 <ce2d4b121fb7545e1ed588e860c8e5fd5ad45224; f1b4e32aca0811aa011c76e5d6cf2fa19224b386 <3cf4fd5316f449811d8baf1bc6978ef5a7b743a9; 5.15.54 <5.15.216; patch: 7.2; patch: 6.1.178; 5.18.11 <5.19; patch: 5.10.265; 5b48f5711f1c630841ab78dcc061de902f0e37bf

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.