{"id":"CVE-2026-31427","title":"netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp","summary":"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_n…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < faa6ea32797a1847790514ff0da1be1d09771580","Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 82baeb871e8f04906bc886273fdf0209e1754eb3","Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 6e5e3c87b7e6212f1d8414fc2e4d158b01e12025","Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6","Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 7edca70751b9bdb5b83eed53cde21eccf3c86147","Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 01f34a80ac23ae90b1909b94b4ed05343a62f646","Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 52fdda318ef2362fc5936385bcb8b3d0328ee629","Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 6a2b724460cb67caed500c508c2ae5cf012e4db4","Linux 2.6.26"],"published":"2026-04-13","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:47:03.009Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31427","references":[{"url":"https://git.kernel.org/stable/c/faa6ea32797a1847790514ff0da1be1d09771580"},{"url":"https://git.kernel.org/stable/c/82baeb871e8f04906bc886273fdf0209e1754eb3"},{"url":"https://git.kernel.org/stable/c/6e5e3c87b7e6212f1d8414fc2e4d158b01e12025"},{"url":"https://git.kernel.org/stable/c/fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6"},{"url":"https://git.kernel.org/stable/c/7edca70751b9bdb5b83eed53cde21eccf3c86147"},{"url":"https://git.kernel.org/stable/c/01f34a80ac23ae90b1909b94b4ed05343a62f646"},{"url":"https://git.kernel.org/stable/c/52fdda318ef2362fc5936385bcb8b3d0328ee629"},{"url":"https://git.kernel.org/stable/c/6a2b724460cb67caed500c508c2ae5cf012e4db4"}],"tags":["cve.org"],"epss":0.0012,"epssPercentile":0.02114,"ingestedAt":"2026-09-08T15:33:26.990Z","slug":"CVE-2026-31427","body":"## Overview\n\nIn 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->sdp_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.\n\n## Affected\n\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < faa6ea32797a1847790514ff0da1be1d09771580`\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 82baeb871e8f04906bc886273fdf0209e1754eb3`\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 6e5e3c87b7e6212f1d8414fc2e4d158b01e12025`\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6`\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 7edca70751b9bdb5b83eed53cde21eccf3c86147`\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 01f34a80ac23ae90b1909b94b4ed05343a62f646`\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 52fdda318ef2362fc5936385bcb8b3d0328ee629`\n- `Linux >= 4ab9e64e5e3c0516577818804aaf13a630d67bc9 < 6a2b724460cb67caed500c508c2ae5cf012e4db4`\n- `Linux 2.6.26`\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":[]}