CVE-2026-31427
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…
Does this matter?
Lower severity and a low EPSS score (0.12%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.12% probability · 2th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-908
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/01f34a80ac23ae90b1909b94b4ed05343a62f646Patch
- https://git.kernel.org/stable/c/52fdda318ef2362fc5936385bcb8b3d0328ee629Patch
- https://git.kernel.org/stable/c/6a2b724460cb67caed500c508c2ae5cf012e4db4Patch
- https://git.kernel.org/stable/c/6e5e3c87b7e6212f1d8414fc2e4d158b01e12025Patch
- https://git.kernel.org/stable/c/7edca70751b9bdb5b83eed53cde21eccf3c86147Patch
- https://git.kernel.org/stable/c/82baeb871e8f04906bc886273fdf0209e1754eb3Patch
- https://git.kernel.org/stable/c/faa6ea32797a1847790514ff0da1be1d09771580Patch
- https://git.kernel.org/stable/c/fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6Patch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.