{"id":"CVE-2026-64073","state":"PUBLISHED","title":"irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nirq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT\n\nOn PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via\nrun_irq_workd(), so irq_work_sync() uses rcuwait() to wait for BUSY==0.\n\nAfter irq_work_single() clears BUSY via atomic_cmpxchg(), it still\ndereferences @work for irq_work_is_hard() and rcuwait_wake_up().\n\nAn irq_work_sync() caller on another CPU that enters after BUSY is cleared\ncan observe BUSY==0 immediately, return, and free the work before those\naccesses complete — causing a use-after-free.\n\nFix this by wrapping run_irq_workd() in guard(rcu)() so that the entire\nirq_work_single() execution is within an RCU read-side critical\nsection. Then add synchronize_rcu() in irq_work_sync() after\nrcuwait_wait_event() to ensure the caller waits for the RCU grace period\nbefore returning, preventing premature frees.","publishedAt":"2026-07-19T15:39:48.463Z","updatedAt":"2026-10-19T20:28:11.133Z","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":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"2dc79362302922cb18f35e262712b5e58de65442","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"eef4f71b46a9929ac33e968538c9dd5d96a02460","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"684a78183c54c23e70d1cba320f7fc184604210b","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"18c0456ea2615b1a743a6db739c74411c3b42bc6","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"81b582784518196eff1050212a046bc29d3a05dd","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"91840be8f710370607f949a627e070896faeddb8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/irq_work.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.16","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/irq_work.c"]}],"references":["https://git.kernel.org/stable/c/2dc79362302922cb18f35e262712b5e58de65442","https://git.kernel.org/stable/c/eef4f71b46a9929ac33e968538c9dd5d96a02460","https://git.kernel.org/stable/c/684a78183c54c23e70d1cba320f7fc184604210b","https://git.kernel.org/stable/c/18c0456ea2615b1a743a6db739c74411c3b42bc6","https://git.kernel.org/stable/c/81b582784518196eff1050212a046bc29d3a05dd","https://git.kernel.org/stable/c/91840be8f710370607f949a627e070896faeddb8"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64073.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64073","state":"PUBLISHED","datePublished":"2026-07-19T15:39:48.463Z","dateUpdated":"2026-10-19T20:28:11.133Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.031Z"},"containers":{"cna":{"title":"irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nirq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT\n\nOn PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via\nrun_irq_workd(), so irq_work_sync() uses rcuwait() to wait for BUSY==0.\n\nAfter irq_work_single() clears BUSY via atomic_cmpxchg(), it still\ndereferences @work for irq_work_is_hard() and rcuwait_wake_up().\n\nAn irq_work_sync() caller on another CPU that enters after BUSY is cleared\ncan observe BUSY==0 immediately, return, and free the work before those\naccesses complete — causing a use-after-free.\n\nFix this by wrapping run_irq_workd() in guard(rcu)() so that the entire\nirq_work_single() execution is within an RCU read-side critical\nsection. Then add synchronize_rcu() in irq_work_sync() after\nrcuwait_wait_event() to ensure the caller waits for the RCU grace period\nbefore returning, preventing premature frees."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"2dc79362302922cb18f35e262712b5e58de65442","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"eef4f71b46a9929ac33e968538c9dd5d96a02460","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"684a78183c54c23e70d1cba320f7fc184604210b","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"18c0456ea2615b1a743a6db739c74411c3b42bc6","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"81b582784518196eff1050212a046bc29d3a05dd","versionType":"git"},{"version":"810979682ccc98dbd83f341c18a2e556c30a7164","status":"affected","lessThan":"91840be8f710370607f949a627e070896faeddb8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/irq_work.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.16","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/irq_work.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/2dc79362302922cb18f35e262712b5e58de65442"},{"url":"https://git.kernel.org/stable/c/eef4f71b46a9929ac33e968538c9dd5d96a02460"},{"url":"https://git.kernel.org/stable/c/684a78183c54c23e70d1cba320f7fc184604210b"},{"url":"https://git.kernel.org/stable/c/18c0456ea2615b1a743a6db739c74411c3b42bc6"},{"url":"https://git.kernel.org/stable/c/81b582784518196eff1050212a046bc29d3a05dd"},{"url":"https://git.kernel.org/stable/c/91840be8f710370607f949a627e070896faeddb8"}],"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 - Exploitation requires reaching irq_work_sync() teardown paths via local syscalls (e.g. perf_event_open/close, bpf map teardown) that queue non-HARD irq_work on PREEMPT_RT; there is no direct network packet or remote-protocol entry point into irq_work.c.\nAC:L - The bug is a cross-CPU race where irq_work_sync() returns after BUSY is cleared while irq_work_single() still dereferences the work; an attacker can control both sides by concurrently closing/freeing a subsystem object and driving irq_work_queue() from another thread/CPU (e.g. perf fasync wakeup vs. close).\nPR:L - Unprivileged local users can reach vulnerable teardown via perf_event_open/close on per-task events (exclude_kernel=1, default paranoid=2) and via bpf() ringbuf/map cleanup when CAP_BPF is available in a user namespace; no init-namespace root is required for the highest-impact paths.\nUI:N - Exploitation is driven entirely by the attacker's own syscalls and threading; no victim interaction such as opening files or mounting filesystems is needed.\nS:U - Successful exploitation corrupts or reads kernel memory and can yield local privilege escalation within the same kernel security authority; it does not inherently cross a VM/host, IOMMU, or container boundary by itself.\nC:H - This is a kernel heap use-after-free: irq_work_single() dereferences a freed irq_work embedded in structures like perf_event or bpf_ringbuf, enabling arbitrary kernel memory disclosure through heap reuse and controlled reads of stale object fields.\nI:H - The UAF permits attacker-controlled reallocation of the freed irq_work container object, providing a standard kernel heap corruption primitive that can be developed into arbitrary write or control-flow hijack, not merely a bounded modification.\nA:H - Use-after-free in irq_work_single() can immediately fault or panic the kernel during post-BUSY dereferences, and repeated triggering via perf/BPF open-close races can cause persistent denial of service on PREEMPT_RT systems."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:38:54.369Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.6.142"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.12.92"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64073","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:36:05.350468Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","type":"CWE","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:28:11.133Z"}}]}}}