{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-44934","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-08-21T05:34:56.664Z","datePublished":"2024-08-26T10:11:25.809Z","dateUpdated":"2026-08-05T11:37:07.351Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:37:07.351Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mcast: wait for previous gc cycles when removing port\n\nsyzbot hit a use-after-free[1] which is caused because the bridge doesn't\nmake sure that all previous garbage has been collected when removing a\nport. What happens is:\n      CPU 1                   CPU 2\n start gc cycle           remove port\n                         acquire gc lock first\n wait for lock\n                         call br_multicasg_gc() directly\n acquire lock now but    free port\n the port can be freed\n while grp timers still\n running\n\nMake sure all previous gc cycles have finished by using flush_work before\nfreeing the port.\n\n[1]\n  BUG: KASAN: slab-use-after-free in br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861\n  Read of size 8 at addr ffff888071d6d000 by task syz.5.1232/9699\n\n  CPU: 1 PID: 9699 Comm: syz.5.1232 Not tainted 6.10.0-rc5-syzkaller-00021-g24ca36a562d6 #0\n  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024\n  Call Trace:\n   <IRQ>\n   __dump_stack lib/dump_stack.c:88 [inline]\n   dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114\n   print_address_description mm/kasan/report.c:377 [inline]\n   print_report+0xc3/0x620 mm/kasan/report.c:488\n   kasan_report+0xd9/0x110 mm/kasan/report.c:601\n   br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861\n   call_timer_fn+0x1a3/0x610 kernel/time/timer.c:1792\n   expire_timers kernel/time/timer.c:1843 [inline]\n   __run_timers+0x74b/0xaf0 kernel/time/timer.c:2417\n   __run_timer_base kernel/time/timer.c:2428 [inline]\n   __run_timer_base kernel/time/timer.c:2421 [inline]\n   run_timer_base+0x111/0x190 kernel/time/timer.c:2437"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is entered only by removing a port from a bridge via local RTNL netlink (`ip link set dev X nomaster`) or the `SIOCBRDELIF` ioctl; received packets alone cannot trigger the port teardown. This requires local system access.\nAC:L - Although this is a race between the mcast gc workqueue and `br_multicast_del_port()`, the attacker drives both sides — populating/expiring port groups to queue gc work while concurrently deleting the port from another CPU — and can retry unboundedly, as demonstrated by the syzbot reproducer.\nPR:L - Bridge creation and port add/remove need only CAP_NET_ADMIN within a network namespace, which any unprivileged user obtains via `unshare -Urn` on default-configured distros; no real root is required.\nUI:N - The attacker performs every step — creating the bridge, generating multicast group state, and removing the port — with no action by any other user.\nS:U - The use-after-free is confined to kernel memory within the same security authority; it does not cross a VM, hypervisor, or IOMMU boundary.\nC:H - The expiring timer reads freed `net_bridge_port` memory (`pg->key.port->br`) and then dereferences that value as a bridge structure; controlling the reclaimed slab yields an arbitrary kernel read primitive and disclosure of kernel memory.\nI:H - After the port slab is reclaimed with attacker-controlled data, the callback performs `spin_lock(&br->multicast_lock)` and structured list/notify operations through the forged pointer, giving controlled kernel writes and a path to control-flow hijack.\nA:H - Even without exploitation the UAF causes a KASAN splat, oops, or panic when the group timer fires against the freed port, crashing the kernel."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_multicast.c"],"versions":[{"version":"e12cec65b5546f19217e26aafb8add6e2fadca18","lessThan":"1e16828020c674b3be85f52685e8b80f9008f50f","status":"affected","versionType":"git"},{"version":"e12cec65b5546f19217e26aafb8add6e2fadca18","lessThan":"0d8b26e10e680c01522d7cc14abe04c3265a928f","status":"affected","versionType":"git"},{"version":"e12cec65b5546f19217e26aafb8add6e2fadca18","lessThan":"e3145ca904fa8dbfd1a5bf0187905bc117b0efce","status":"affected","versionType":"git"},{"version":"e12cec65b5546f19217e26aafb8add6e2fadca18","lessThan":"b2f794b168cf560682ff976b255aa6d29d14a658","status":"affected","versionType":"git"},{"version":"e12cec65b5546f19217e26aafb8add6e2fadca18","lessThan":"92c4ee25208d0f35dafc3213cdf355fbe449e078","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_multicast.c"],"versions":[{"version":"5.10","status":"affected"},{"version":"0","lessThan":"5.10","status":"unaffected","versionType":"semver"},{"version":"5.15.165","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.105","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.46","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.10.5","lessThanOrEqual":"6.10.*","status":"unaffected","versionType":"semver"},{"version":"6.11","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"5.15.165"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.1.105"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.6.46"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.10.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.11"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/1e16828020c674b3be85f52685e8b80f9008f50f"},{"url":"https://git.kernel.org/stable/c/0d8b26e10e680c01522d7cc14abe04c3265a928f"},{"url":"https://git.kernel.org/stable/c/e3145ca904fa8dbfd1a5bf0187905bc117b0efce"},{"url":"https://git.kernel.org/stable/c/b2f794b168cf560682ff976b255aa6d29d14a658"},{"url":"https://git.kernel.org/stable/c/92c4ee25208d0f35dafc3213cdf355fbe449e078"}],"title":"net: bridge: mcast: wait for previous gc cycles when removing port","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2024-44934","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-09-10T15:27:51.533304Z"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-09-12T17:32:55.981Z"}},{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2025-11-03T22:13:38.280Z"}}]}}