{"id":"CVE-2026-52933","state":"PUBLISHED","title":"io_uring/poll: fix signed comparison in io_poll_get_ownership()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/poll: fix signed comparison in io_poll_get_ownership()\n\nio_poll_get_ownership() uses a signed comparison to check whether\npoll_refs has reached the threshold for the slowpath:\n\n    if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))\n\natomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG\n(BIT(31)) is set in poll_refs, the value becomes negative in\nsigned arithmetic, so the >= 128 comparison always evaluates to\nfalse and the slowpath is never taken.\n\nFix this by casting the atomic_read() result to unsigned int\nbefore the comparison, so that the cancel flag is treated as a\nlarge positive value and correctly triggers the slowpath.","publishedAt":"2026-06-24T07:14:24.678Z","updatedAt":"2026-10-19T19:47:08.287Z","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":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"81bf96b0abbfa4cd47ea32e12596aed3855fb2f3","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"cf522703d4f194991615763697ae25a3f9539763","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"fc47043f3d9af3efa407665b47f8378ec691ba18","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"ea0697129807d718037f618221037aa0660ee3c5","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"c6d191164dc81838d8dbf452a6000f68c558d1ae","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"326941b22806cbf2df1fbfe902b7908b368cce42","versionType":"git"},{"version":"4b702b7d11ce1b9d26fc6d7c5a7ef4ac1d455048","status":"affected","versionType":"git"},{"version":"bc4e6ee16778149811333a969a7a893d4cc110c5","status":"affected","versionType":"git"},{"version":"5.15.82","status":"affected","lessThan":"5.16","versionType":"semver"},{"version":"6.0.11","status":"affected","lessThan":"6.1","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["io_uring/poll.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.1","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.140","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.86","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","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":["io_uring/poll.c"]}],"references":["https://git.kernel.org/stable/c/81bf96b0abbfa4cd47ea32e12596aed3855fb2f3","https://git.kernel.org/stable/c/cf522703d4f194991615763697ae25a3f9539763","https://git.kernel.org/stable/c/fc47043f3d9af3efa407665b47f8378ec691ba18","https://git.kernel.org/stable/c/ea0697129807d718037f618221037aa0660ee3c5","https://git.kernel.org/stable/c/c6d191164dc81838d8dbf452a6000f68c558d1ae","https://git.kernel.org/stable/c/326941b22806cbf2df1fbfe902b7908b368cce42","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":["CWE-190"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/52xxx/CVE-2026-52933.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-52933","state":"PUBLISHED","datePublished":"2026-06-24T07:14:24.678Z","dateUpdated":"2026-10-19T19:47:08.287Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.369Z"},"containers":{"cna":{"title":"io_uring/poll: fix signed comparison in io_poll_get_ownership()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/poll: fix signed comparison in io_poll_get_ownership()\n\nio_poll_get_ownership() uses a signed comparison to check whether\npoll_refs has reached the threshold for the slowpath:\n\n    if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))\n\natomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG\n(BIT(31)) is set in poll_refs, the value becomes negative in\nsigned arithmetic, so the >= 128 comparison always evaluates to\nfalse and the slowpath is never taken.\n\nFix this by casting the atomic_read() result to unsigned int\nbefore the comparison, so that the cancel flag is treated as a\nlarge positive value and correctly triggers the slowpath."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"81bf96b0abbfa4cd47ea32e12596aed3855fb2f3","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"cf522703d4f194991615763697ae25a3f9539763","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"fc47043f3d9af3efa407665b47f8378ec691ba18","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"ea0697129807d718037f618221037aa0660ee3c5","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"c6d191164dc81838d8dbf452a6000f68c558d1ae","versionType":"git"},{"version":"a26a35e9019fd70bf3cf647dcfdae87abc7bacea","status":"affected","lessThan":"326941b22806cbf2df1fbfe902b7908b368cce42","versionType":"git"},{"version":"4b702b7d11ce1b9d26fc6d7c5a7ef4ac1d455048","status":"affected","versionType":"git"},{"version":"bc4e6ee16778149811333a969a7a893d4cc110c5","status":"affected","versionType":"git"},{"version":"5.15.82","status":"affected","lessThan":"5.16","versionType":"semver"},{"version":"6.0.11","status":"affected","lessThan":"6.1","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["io_uring/poll.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.1","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.140","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.86","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","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":["io_uring/poll.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/81bf96b0abbfa4cd47ea32e12596aed3855fb2f3"},{"url":"https://git.kernel.org/stable/c/cf522703d4f194991615763697ae25a3f9539763"},{"url":"https://git.kernel.org/stable/c/fc47043f3d9af3efa407665b47f8378ec691ba18"},{"url":"https://git.kernel.org/stable/c/ea0697129807d718037f618221037aa0660ee3c5"},{"url":"https://git.kernel.org/stable/c/c6d191164dc81838d8dbf452a6000f68c558d1ae"},{"url":"https://git.kernel.org/stable/c/326941b22806cbf2df1fbfe902b7908b368cce42"}],"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 reached by local `io_uring_setup()`/`io_uring_enter()` submissions of poll and cancel operations, not by remote packets or physical access.\nAC:L - An attacker can create the ring, choose pollable file descriptors, submit cancels/removes, and generate concurrent wakeups; the race participants are attacker-controlled.\nPR:L - With the default `io_uring_disabled=0`, an unprivileged local user can create and use io_uring; no real root or init-namespace capability is required.\nUI:N - Exploitation does not require another user to mount, open, or process anything; the attacker drives the syscall and file-descriptor activity directly.\nS:U - This is a kernel request-lifetime/ownership bug within the same host kernel security authority, not a VM, IOMMU, or separate security-scope escape.\nC:H - The signedness bug defeats the poll_refs overflow/ownership slow path after cancellation, allowing ref-bit wrap and duplicate ownership/completion of an `io_kiocb`; that is UAF-style kernel memory corruption with plausible memory disclosure.\nI:H - The same duplicate ownership/completion and request lifetime corruption can plausibly be shaped into arbitrary kernel memory modification or control-flow compromise, so integrity impact is high.\nA:H - At minimum, corrupted poll ownership and duplicate completion can trigger kernel warnings, NULL dereferences, UAF crashes, or hangs in a local attacker-controlled loop."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:31:51.192Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.6.140"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.12.86"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.18.27"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.0.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.82"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0.11"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.6","status":"affected","lessThan":"*","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.7","status":"affected","lessThan":"*","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T01:21:56.252Z"},"x_adpType":"supplier"},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-52933","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:22:58.731719Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-190","lang":"en","type":"CWE","description":"CWE-190 Integer Overflow or Wraparound"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:47:08.287Z"}}]}}}