netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp

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Summary

CVECVE-2026-31427
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-13 14:16:12 UTC
Updated2026-07-14 13:18:40 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.000320000 probability, percentile 0.092520000 (date 2026-04-21)

Problem Types: CWE-908

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 faa6ea32797a1847790514ff0da1be1d09771580 git Not specified
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 82baeb871e8f04906bc886273fdf0209e1754eb3 git Not specified
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 6e5e3c87b7e6212f1d8414fc2e4d158b01e12025 git Not specified
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6 git Not specified
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 7edca70751b9bdb5b83eed53cde21eccf3c86147 git Not specified
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 01f34a80ac23ae90b1909b94b4ed05343a62f646 git Not specified
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 52fdda318ef2362fc5936385bcb8b3d0328ee629 git Not specified
CNA Linux Linux affected 4ab9e64e5e3c0516577818804aaf13a630d67bc9 6a2b724460cb67caed500c508c2ae5cf012e4db4 git Not specified
CNA Linux Linux affected 2.6.26 Not specified
CNA Linux Linux unaffected 2.6.26 semver Not specified
CNA Linux Linux unaffected 5.10.253 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.203 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.168 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.131 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.80 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.21 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.11 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/6a2b724460cb67caed500c508c2ae5cf012e4db4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/6e5e3c87b7e6212f1d8414fc2e4d158b01e12025 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-082556.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/7edca70751b9bdb5b83eed53cde21eccf3c86147 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/52fdda318ef2362fc5936385bcb8b3d0328ee629 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/faa6ea32797a1847790514ff0da1be1d09771580 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/01f34a80ac23ae90b1909b94b4ed05343a62f646 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/82baeb871e8f04906bc886273fdf0209e1754eb3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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