CVE-2026-31427
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp process_sdp() declares union nf_inet_addr rtp_addr on the stack and passes it to the nf_nat_sip sdp_session hook after walking the SDP media descriptions. However rtp_addr is only initialized inside the media loop when a recognized media type with a non-zero port is found. If the SDP body contains no m= lines, only inactive media sections (m=audio 0 ...) or only unrecognized media types, rtp_addr is never assigned. Despite that, the function still calls hooks->sdp_session() with &rtp_addr, causing nf_nat_sdp_session() to format the stale stack value as an IP address and rewrite the SDP session owner and connection lines with it. With CONFIG_INIT_STACK_ALL_ZERO (default on most distributions) this results in the session-level o= and c= addresses being rewritten to 0.0.0.0 for inactive SDP sessions. Without stack auto-init the rewritten address is whatever happened to be on the stack. Fix this by pre-initializing rtp_addr from the session-level connection address (caddr) when available, and tracking via a have_rtp_addr flag whether any valid address was established. Skip the sdp_session hook entirely when no valid address exists.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | fixed | 6.1.170-1 |
| debian | forky | fixed | 6.19.11-1 |
| debian | sid | fixed | 6.19.11-1 |
| debian | trixie | fixed | 6.12.85-1 |
| debian | bullseye | fixed | 6.1.170-1~deb11u1 |
| linux-kernel | affected | 5.10.253 | |
| linux-kernel | 7.0 | affected | |
References
- https://git.kernel.org/stable/c/01f34a80ac23ae90b1909b94b4ed05343a62f646
- https://git.kernel.org/stable/c/52fdda318ef2362fc5936385bcb8b3d0328ee629
- https://git.kernel.org/stable/c/6a2b724460cb67caed500c508c2ae5cf012e4db4
- https://git.kernel.org/stable/c/6e5e3c87b7e6212f1d8414fc2e4d158b01e12025
- https://git.kernel.org/stable/c/7edca70751b9bdb5b83eed53cde21eccf3c86147
- https://git.kernel.org/stable/c/82baeb871e8f04906bc886273fdf0209e1754eb3
- https://git.kernel.org/stable/c/faa6ea32797a1847790514ff0da1be1d09771580
- https://git.kernel.org/stable/c/fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6
- https://www.suse.com/security/cve/CVE-2026-31427.html
- https://security-tracker.debian.org/tracker/CVE-2026-31427
CWEs
CWE-908
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.