{"id":"CVE-2025-39872","state":"PUBLISHED","title":"hsr: hold rcu and dev lock for hsr_get_port_ndev","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nhsr: hold rcu and dev lock for hsr_get_port_ndev\n\nhsr_get_port_ndev calls hsr_for_each_port, which need to hold rcu lock.\nOn the other hand, before return the port device, we need to hold the\ndevice reference to avoid UaF in the caller function.","publishedAt":"2025-09-23T06:00:45.528Z","updatedAt":"2026-08-05T12:05:48.806Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ef964411c8ca775967355d855abc56aeaca3c867","status":"affected","lessThan":"9433ba79c2ec3ec7c9a711748701549339c3438c","versionType":"git"},{"version":"9c10dd8eed74de9e8adeb820939f8745cd566d4a","status":"affected","lessThan":"68a6729afd3e8e9a2a32538642ce92b96ccf9b1d","versionType":"git"},{"version":"9c10dd8eed74de9e8adeb820939f8745cd566d4a","status":"affected","lessThan":"847748fc66d08a89135a74e29362a66ba4e3ab15","versionType":"git"},{"version":"6.12.63","status":"affected","lessThan":"6.12.64","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/ti/icssg/icssg_prueth.c","net/hsr/hsr_device.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.12.64","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.8","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/ti/icssg/icssg_prueth.c","net/hsr/hsr_device.c"]}],"references":["https://git.kernel.org/stable/c/9433ba79c2ec3ec7c9a711748701549339c3438c","https://git.kernel.org/stable/c/68a6729afd3e8e9a2a32538642ce92b96ccf9b1d","https://git.kernel.org/stable/c/847748fc66d08a89135a74e29362a66ba4e3ab15"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/39xxx/CVE-2025-39872.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-39872","state":"PUBLISHED","datePublished":"2025-09-23T06:00:45.528Z","dateUpdated":"2026-08-05T12:05:48.806Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.144Z"},"containers":{"cna":{"title":"hsr: hold rcu and dev lock for hsr_get_port_ndev","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nhsr: hold rcu and dev lock for hsr_get_port_ndev\n\nhsr_get_port_ndev calls hsr_for_each_port, which need to hold rcu lock.\nOn the other hand, before return the port device, we need to hold the\ndevice reference to avoid UaF in the caller function."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ef964411c8ca775967355d855abc56aeaca3c867","status":"affected","lessThan":"9433ba79c2ec3ec7c9a711748701549339c3438c","versionType":"git"},{"version":"9c10dd8eed74de9e8adeb820939f8745cd566d4a","status":"affected","lessThan":"68a6729afd3e8e9a2a32538642ce92b96ccf9b1d","versionType":"git"},{"version":"9c10dd8eed74de9e8adeb820939f8745cd566d4a","status":"affected","lessThan":"847748fc66d08a89135a74e29362a66ba4e3ab15","versionType":"git"},{"version":"6.12.63","status":"affected","lessThan":"6.12.64","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/ti/icssg/icssg_prueth.c","net/hsr/hsr_device.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.12.64","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.8","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/ti/icssg/icssg_prueth.c","net/hsr/hsr_device.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9433ba79c2ec3ec7c9a711748701549339c3438c"},{"url":"https://git.kernel.org/stable/c/68a6729afd3e8e9a2a32538642ce92b96ccf9b1d"},{"url":"https://git.kernel.org/stable/c/847748fc66d08a89135a74e29362a66ba4e3ab15"}],"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 from local socket/netlink operations — a multicast group join on the HSR master propagates via `hsr_set_rx_mode()` to the ICSSG slave's `ndo_set_rx_mode`, which queues the work that calls `hsr_get_port_ndev()`. A remote peer on the HSR ring cannot induce multicast address changes or HSR port reconfiguration, so this is not network-reachable.\nAC:L - The attacker fully controls the traversal side of the race by looping `IP_ADD_MEMBERSHIP`/`IP_DROP_MEMBERSHIP` to repeatedly queue `emac_ndo_set_rx_mode_work`, and the walk runs in preemptible process context with no RCU or RTNL held, so no tight timing window must be won — only overlap with a port-list mutation, which can be retried indefinitely.\nPR:L - Triggering the vulnerable `hsr_get_port_ndev()` traversal requires only an ordinary unprivileged UDP socket performing a multicast group join on the HSR interface; no capability check exists anywhere on that path. Widening the race window via HSR port reconfiguration needs only CAP_NET_ADMIN, which per kernel CNA guidance is scored as Low.\nUI:N - The entire sequence is driven by the attacker's own socket operations against an already-configured HSR-offload interface. No victim action is needed.\nS:U - The use-after-free corrupts kernel memory within the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The unlocked RCU walk dereferences a freed `hsr_port` and the returned `net_device` is used without a reference, and `netdev_priv()` on that freed device is read as a `prueth_emac` — a use-after-free read whose contents the attacker can groom via heap spray, yielding kernel memory disclosure and pointer leakage.\nI:H - `icssg_fdb_setup()` performs `++(emac->prueth->icssg_hwcmdseq)` — a pointer loaded out of the freed object and then written through — plus further writes into PRU shared memory at addresses derived from freed data, giving a controllable write primitive suitable for control-flow hijacking after heap reuse.\nA:H - Following a `kfree_rcu()`-freed list node and dereferencing a freed `net_device` reliably produces an oops/panic (and slab corruption) even when not exploited further, and the attacker can retrigger it repeatedly on an industrial redundancy device."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:05:48.806Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.63","versionEndExcluding":"6.12.64"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"6.16.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"6.17"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}