CVE-2026-63827

CVE CVE-2026-63827EUVD EUVD-2026-45493Veröffentlicht 2026-07-19T12:02:22.000ZZuletzt geändert 2026-08-05T12:36:10.000ZCVSS 7.8

Was das Advisory beschreibt

In the Linux kernel, the following vulnerability has been resolved: apparmor: fix use-after-free in rawdata dedup loop aa_replace_profiles() walks ns->rawdata_list to dedup the incoming policy blob against entries already attached to existing profiles. Per the kernel-doc on struct aa_loaddata, list membership does not hold a reference: profiles hold pcount, and when the last pcount drops, do_ploaddata_rmfs() is queued on a workqueue that takes ns->lock and removes the entry. Between dropping the last pcount and the workqueue running, an entry remains on the list with pcount == 0. aa_get_profile_loaddata() is an unconditional kref_get() on pcount, so when the dedup loop hits such an entry, refcount hardening reports refcount_t: addition on 0; use-after-free. inside aa_replace_profiles(), and the poisoned counter then trips "saturated" and "underflow" warnings on the subsequent uses of the same loaddata. Before commit a0b7091c4de4 ("apparmor: fix race on rawdata dereference") the dedup path used a get_unless_zero-style helper on a single counter, so the existing "if (tmp)" guard was meaningful. The split-refcount refactor introduced aa_get_profile_loaddata(), which has plain kref_get() semantics, and the guard quietly became a no-op. Introduce aa_get_profile_loaddata_not0(), matching the existing _not0 convention used by aa_get_profile_not0(), and use it for the rawdata_list dedup lookup so dying entries are skipped. Reproduced on x86_64 with v7.1-rc5 in QEMU+KVM running Ubuntu 24.04 + stress-ng 0.17.06: stress-ng --apparmor 1 --klog-check --timeout 60s Without this patch the three refcount_t warnings fire within a few seconds. With it the same 60 s run is clean. Coverage is a smoke-test only; a longer soak with CONFIG_KASAN, CONFIG_KCSAN and CONFIG_PROVE_LOCKING would be welcome from anyone with the cycles.

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: 6.6.144; patch: 6.18.38; 7.0; patch: 7.2-rc1; 6.19.8 <6.20; 5.10.253 <5.10.261; patch: 5.15.212; f9761add6d100962a23996cb68f3d6abdd4d1815 <ce261a20b41db522e320a41bbf1292bf85af66df; 6ef1f2926c41ab96952d9696d55a052f1b3a9418 <15fd83a1e42ede15070968806bb6c8b1a5170688; 6b6ba87579c7e7c669e0bec91823e7fb693bc5df <a7a2890028f16e5b0af0bb005d80fcb32559cca3; a0b7091c4de45a7325c8780e6934a894f92ac86b <6f060496d03e4dc560a40f73770bd08335cb7a27; patch: 0; 5.15.203 <5.15.212; patch: 6.1.177; 6.1.169 <6.1.177; patch: 5.10.261; a0b7091c4de45a7325c8780e6934a894f92ac86b <5e34fa9f6f7cd688ae153fff13139a5cf2d42339; af782cc8871e3683ddd5a3cd2f7df526599863a9 <c3ca2631073b2cef06824fd2bfc452ff7a1023de; 6.18.18 <6.18.38; 6.12.77 <6.12.95; patch: 6.12.95; patch: 7.1.3; 763e838adc3c7ec5a7df2990ce84cad951e42721; d9d8560b9b7932f8cffc4c068c14289220900f79 <b17f0c59cc1525765625cf07d0391b7f9c1ed7e5; 3b8e77c7abab40e6de9ad9de730d77984a498840 <643221da57dbb1a8fd800610331cf1ec27969f71; 6.6.130 <6.6.144

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.