{"id":"CVE-2026-53191","state":"PUBLISHED","title":"io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries\n\nWhen a bundle recv retries inside io_recv_finish(), the merge logic OR\nthe saved cflags from the previous iteration with the cflags returned by\nthe new iteration:\n  cflags = req->cqe.flags | (cflags & CQE_F_MASK);\n\nBits listed in CQE_F_MASK are inherited from the new iteration, and all\nother bits (notably IORING_CQE_F_BUFFER and the buffer ID) come from the\nsaved cflags. Before this change CQE_F_MASK covered only\nIORING_CQE_F_SOCK_NONEMPTY and IORING_CQE_F_MORE.\n\nWhen using provided buffer rings (IOU_PBUF_RING_INC) with incremental\nmode, and bundle recv, io_kbuf_inc_commit() can leave the head ring\nentry partially consumed, __io_put_kbufs() then sets\nIORING_CQE_F_BUF_MORE on the returned cflags so userspace knows the\nbuffer ID will be reused for subsequent completions.\n\nBecause IORING_CQE_F_BUF_MORE was not in CQE_F_MASK, the merge above\nsilently dropped it whenever the final retry iteration partially\nconsumed the buffer, and the subsequent req->cqe.flags = cflags &\n~CQE_F_MASK save would have left a stale IORING_CQE_F_BUF_MORE in the\ncarried-over cflags had one been present. Userspace would then\nwrongfully advance it ring head past an entry the kernel still uses.\n\nAdd IORING_CQE_F_BUF_MORE to CQE_F_MASK so it is both inherited from the\nnew iteration into the user-visible CQE and stripped from the saved\ncflags between iterations.","publishedAt":"2026-06-25T08:39:03.052Z","updatedAt":"2026-10-19T19:57:27.637Z","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":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"f40570fda3f3a1f96aeaa4aef665ba274b2810b5","versionType":"git"},{"version":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"0bbc9481f970b0b4ddb08cfa464db1cc93b74b56","versionType":"git"},{"version":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"4973232a67e4137ab9399f504f7f2bdd847f96d2","versionType":"git"},{"version":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"ed46f39c47eb5530a9c161481a2080d3a869cfaf","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["io_uring/net.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.94","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.36","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.13","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/net.c"]}],"references":["https://git.kernel.org/stable/c/f40570fda3f3a1f96aeaa4aef665ba274b2810b5","https://git.kernel.org/stable/c/0bbc9481f970b0b4ddb08cfa464db1cc93b74b56","https://git.kernel.org/stable/c/4973232a67e4137ab9399f504f7f2bdd847f96d2","https://git.kernel.org/stable/c/ed46f39c47eb5530a9c161481a2080d3a869cfaf"],"weaknesses":["CWE-682"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53191.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53191","state":"PUBLISHED","datePublished":"2026-06-25T08:39:03.052Z","dateUpdated":"2026-10-19T19:57:27.637Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.390Z"},"containers":{"cna":{"title":"io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries\n\nWhen a bundle recv retries inside io_recv_finish(), the merge logic OR\nthe saved cflags from the previous iteration with the cflags returned by\nthe new iteration:\n  cflags = req->cqe.flags | (cflags & CQE_F_MASK);\n\nBits listed in CQE_F_MASK are inherited from the new iteration, and all\nother bits (notably IORING_CQE_F_BUFFER and the buffer ID) come from the\nsaved cflags. Before this change CQE_F_MASK covered only\nIORING_CQE_F_SOCK_NONEMPTY and IORING_CQE_F_MORE.\n\nWhen using provided buffer rings (IOU_PBUF_RING_INC) with incremental\nmode, and bundle recv, io_kbuf_inc_commit() can leave the head ring\nentry partially consumed, __io_put_kbufs() then sets\nIORING_CQE_F_BUF_MORE on the returned cflags so userspace knows the\nbuffer ID will be reused for subsequent completions.\n\nBecause IORING_CQE_F_BUF_MORE was not in CQE_F_MASK, the merge above\nsilently dropped it whenever the final retry iteration partially\nconsumed the buffer, and the subsequent req->cqe.flags = cflags &\n~CQE_F_MASK save would have left a stale IORING_CQE_F_BUF_MORE in the\ncarried-over cflags had one been present. Userspace would then\nwrongfully advance it ring head past an entry the kernel still uses.\n\nAdd IORING_CQE_F_BUF_MORE to CQE_F_MASK so it is both inherited from the\nnew iteration into the user-visible CQE and stripped from the saved\ncflags between iterations."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"f40570fda3f3a1f96aeaa4aef665ba274b2810b5","versionType":"git"},{"version":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"0bbc9481f970b0b4ddb08cfa464db1cc93b74b56","versionType":"git"},{"version":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"4973232a67e4137ab9399f504f7f2bdd847f96d2","versionType":"git"},{"version":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a","status":"affected","lessThan":"ed46f39c47eb5530a9c161481a2080d3a869cfaf","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["io_uring/net.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.94","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.36","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.13","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/net.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f40570fda3f3a1f96aeaa4aef665ba274b2810b5"},{"url":"https://git.kernel.org/stable/c/0bbc9481f970b0b4ddb08cfa464db1cc93b74b56"},{"url":"https://git.kernel.org/stable/c/4973232a67e4137ab9399f504f7f2bdd847f96d2"},{"url":"https://git.kernel.org/stable/c/ed46f39c47eb5530a9c161481a2080d3a869cfaf"}],"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 through locally submitted io_uring receive operations with buffer selection and bundle recv; a remote peer can influence socket data, but cannot select these io_uring flags or register the buffer ring by itself.\nAC:L - The trigger is deterministic once the attacker controls the io_uring setup, buffer sizes, and socket data pattern; no uncontrolled race or rare kernel state is required.\nPR:L - A basic unprivileged local user can normally create an io_uring instance, register an incremental provided-buffer ring, and submit IORING_OP_RECV, absent non-default sysctl or LSM restrictions.\nUI:N - No separate victim interaction is required after the attacker submits the crafted io_uring operations and supplies socket data.\nS:U - This is a kernel/io_uring buffer ownership bug and does not cross a VM, IOMMU, or other separate security authority boundary.\nC:H - The dropped BUF_MORE flag can make userspace reclaim a buffer that the kernel will continue to use, creating a use-after-recycle style memory corruption primitive in an affected io_uring consumer.\nI:H - The stale ownership state can cause later kernel receives to write attacker-controlled socket data into memory that the application has legitimately reused, which is a high-impact corruption primitive.\nA:H - The same buffer reuse corruption can crash or destabilize an affected io_uring receiver, and repeated triggering is under attacker control once the vulnerable operation pattern is in use."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:33:57.520Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.94"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.18.36"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.0.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-53191","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:26:32.754734Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-682","lang":"en","type":"CWE","description":"CWE-682 Incorrect Calculation"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:57:27.637Z"}}]}}}