{"id":"CVE-2026-98525","title":"mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()","summary":"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 ove…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < 09299addab11857e92eca55cd8ef3350b927c90c","Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < e35cb500dd14882f8dee61783fccd1823fd3ab0d","Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < f178300e2f56ca9ec2a3a0090608730bbee0af7b","Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < 26cc0e69cce062cd3aa6fae33074684669c35a71","Linux 5.18"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:17:43.216Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98525","references":[{"url":"https://git.kernel.org/stable/c/09299addab11857e92eca55cd8ef3350b927c90c"},{"url":"https://git.kernel.org/stable/c/e35cb500dd14882f8dee61783fccd1823fd3ab0d"},{"url":"https://git.kernel.org/stable/c/f178300e2f56ca9ec2a3a0090608730bbee0af7b"},{"url":"https://git.kernel.org/stable/c/26cc0e69cce062cd3aa6fae33074684669c35a71"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.281Z","slug":"CVE-2026-98525","body":"## Overview\n\nIn 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->keys list\nand matches netid, req_tag, peer_addr, and manual_alloc, without\nchecking whether tmp->sk == &msk->sk. 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->keys via sklist) instead of the\nnamespace-wide &mns->keys 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).\n\n## Affected\n\n- `Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < 09299addab11857e92eca55cd8ef3350b927c90c`\n- `Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < e35cb500dd14882f8dee61783fccd1823fd3ab0d`\n- `Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < f178300e2f56ca9ec2a3a0090608730bbee0af7b`\n- `Linux >= 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa < 26cc0e69cce062cd3aa6fae33074684669c35a71`\n- `Linux 5.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}