{"id":"CVE-2026-98525","summary":"mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()\n\nWhen a socket transmits a packet with MCTP_TAG_PREALLOC set,\nmctp_lookup_prealloc_tag() iterates over the per-netns &mns-\u003ekeys list\nand matches netid, req_tag, peer_addr, and manual_alloc, without\nchecking whether tmp-\u003esk == &msk-\u003esk. This allows any MCTP socket in the\nsame network namespace to use and consume another socket's preallocated\ntag.\n\nIterate the socket's own tag list (&msk-\u003ekeys via sklist) instead of the\nnamespace-wide &mns-\u003ekeys list in mctp_lookup_prealloc_tag(), ensuring\nthat only tags allocated by msk are matched.\n\nTested in QEMU against Linux 7.3.0-rc3 by allocating a manual tag\n(0x18) on socket A via SIOCMCTPALLOCTAG for peer EID 9 and sending a\n4-byte message with MCTP_TAG_PREALLOC from socket B in the same network\nnamespace. On the unfixed kernel, sendto(sock_b) using socket A's\npreallocated tag succeeds (ret = 4); with this patch applied,\nsendto(sock_b) fails with -ENOENT (errno = 2) while sendto(sock_a)\nsucceeds (ret = 4).","modified":"2026-10-19T02:46:22.586962531Z","published":"2026-10-18T15:17:43.216Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98525.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/09299addab11857e92eca55cd8ef3350b927c90c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/26cc0e69cce062cd3aa6fae33074684669c35a71"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e35cb500dd14882f8dee61783fccd1823fd3ab0d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f178300e2f56ca9ec2a3a0090608730bbee0af7b"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98525.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98525"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"63ed1aab3d40aa61aaa66819bdce9377ac7f40fa"},{"fixed":"09299addab11857e92eca55cd8ef3350b927c90c"},{"fixed":"e35cb500dd14882f8dee61783fccd1823fd3ab0d"},{"fixed":"f178300e2f56ca9ec2a3a0090608730bbee0af7b"},{"fixed":"26cc0e69cce062cd3aa6fae33074684669c35a71"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98525.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.18.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.55"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98525.json"}}],"schema_version":"1.9.0"}