{"id":"CVE-2026-53191","summary":"io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries","details":"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-\u003ecqe.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-\u003ecqe.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.","modified":"2026-07-08T08:09:46.762056689Z","published":"2026-06-25T08:39:03.052Z","related":["CGA-xv7c-877c-f2jm"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53191.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0bbc9481f970b0b4ddb08cfa464db1cc93b74b56"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4973232a67e4137ab9399f504f7f2bdd847f96d2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ed46f39c47eb5530a9c161481a2080d3a869cfaf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f40570fda3f3a1f96aeaa4aef665ba274b2810b5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53191.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53191"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ae98dbf43d755b4e111fcd086e53939bef3e9a1a"},{"fixed":"f40570fda3f3a1f96aeaa4aef665ba274b2810b5"},{"fixed":"0bbc9481f970b0b4ddb08cfa464db1cc93b74b56"},{"fixed":"4973232a67e4137ab9399f504f7f2bdd847f96d2"},{"fixed":"ed46f39c47eb5530a9c161481a2080d3a869cfaf"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53191.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.12.0"},{"fixed":"6.12.94"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.36"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53191.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}