{"id":"CVE-2026-53191","title":"io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries","summary":"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…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < f40570fda3f3a1f96aeaa4aef665ba274b2810b5","Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < 0bbc9481f970b0b4ddb08cfa464db1cc93b74b56","Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < 4973232a67e4137ab9399f504f7f2bdd847f96d2","Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < ed46f39c47eb5530a9c161481a2080d3a869cfaf","Linux 6.12"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:26:32.754734Z"},"published":"2026-06-25","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:31:36.281Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-53191","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"}],"tags":["cve.org"],"epss":0.00129,"epssPercentile":0.02218,"ingestedAt":"2026-10-16T17:24:46.735Z","slug":"CVE-2026-53191","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < f40570fda3f3a1f96aeaa4aef665ba274b2810b5`\n- `Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < 0bbc9481f970b0b4ddb08cfa464db1cc93b74b56`\n- `Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < 4973232a67e4137ab9399f504f7f2bdd847f96d2`\n- `Linux >= ae98dbf43d755b4e111fcd086e53939bef3e9a1a < ed46f39c47eb5530a9c161481a2080d3a869cfaf`\n- `Linux 6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}