{"id":"CVE-2026-31427","summary":"netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp\n\nprocess_sdp() declares union nf_inet_addr rtp_addr on the stack and\npasses it to the nf_nat_sip sdp_session hook after walking the SDP\nmedia descriptions. However rtp_addr is only initialized inside the\nmedia loop when a recognized media type with a non-zero port is found.\n\nIf the SDP body contains no m= lines, only inactive media sections\n(m=audio 0 ...) or only unrecognized media types, rtp_addr is never\nassigned. Despite that, the function still calls hooks-\u003esdp_session()\nwith &rtp_addr, causing nf_nat_sdp_session() to format the stale stack\nvalue as an IP address and rewrite the SDP session owner and connection\nlines with it.\n\nWith CONFIG_INIT_STACK_ALL_ZERO (default on most distributions) this\nresults in the session-level o= and c= addresses being rewritten to\n0.0.0.0 for inactive SDP sessions. Without stack auto-init the\nrewritten address is whatever happened to be on the stack.\n\nFix this by pre-initializing rtp_addr from the session-level connection\naddress (caddr) when available, and tracking via a have_rtp_addr flag\nwhether any valid address was established. Skip the sdp_session hook\nentirely when no valid address exists.","modified":"2026-05-15T04:14:34.746880286Z","published":"2026-04-13T13:40:30.280Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31427.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/01f34a80ac23ae90b1909b94b4ed05343a62f646"},{"type":"WEB","url":"https://git.kernel.org/stable/c/52fdda318ef2362fc5936385bcb8b3d0328ee629"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6a2b724460cb67caed500c508c2ae5cf012e4db4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6e5e3c87b7e6212f1d8414fc2e4d158b01e12025"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7edca70751b9bdb5b83eed53cde21eccf3c86147"},{"type":"WEB","url":"https://git.kernel.org/stable/c/82baeb871e8f04906bc886273fdf0209e1754eb3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/faa6ea32797a1847790514ff0da1be1d09771580"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31427.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31427"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.26"},{"fixed":"5.10.253"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.168"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.131"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.80"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.21"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31427.json"}}],"schema_version":"1.7.5"}