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Back to active CVEs
Medium ยท CVSS 5.5CVE-2026-31427

netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdpCVE-2026-31427

Answer in brief

CVE-2026-31427 records a Medium severity (CVSS 5.5) vulnerability in netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Apr 13, 2026Updated Oct 15, 2026Source checked Nov 4, 2026First seen by HOL Jul 14, 2026Material review Oct 15, 2026
Upstream Advisory

Key facts

Risk
Medium ยท CVSS 5.5
Exploitation
Not marked as known exploited
Affected software
17 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Affected products and reported versions
ProductAffected versionsFixed versions
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*Not reportedNot reported
Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Linux/Linuxgeneric>=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <faa6ea32797a1847790514ff0da1be1d09771580 || >=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <82baeb871e8f04906bc886273fdf0209e1754eb3 || >=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <6e5e3c87b7e6212f1d8414fc2e4d158b01e12025 || >=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6 || >=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <7edca70751b9bdb5b83eed53cde21eccf3c86147 || >=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <01f34a80ac23ae90b1909b94b4ed05343a62f646 || >=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <52fdda318ef2362fc5936385bcb8b3d0328ee629 || >=4ab9e64e5e3c0516577818804aaf13a630d67bc9 <6a2b724460cb67caed500c508c2ae5cf012e4db4faa6ea32797a1847790514ff0da1be1d09771580, 82baeb871e8f04906bc886273fdf0209e1754eb3, 6e5e3c87b7e6212f1d8414fc2e4d158b01e12025, fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6, 7edca70751b9bdb5b83eed53cde21eccf3c86147, 01f34a80ac23ae90b1909b94b4ed05343a62f646, 52fdda318ef2362fc5936385bcb8b3d0328ee629, 6a2b724460cb67caed500c508c2ae5cf012e4db4
Linux/Linuxgeneric2.6.26Not reported
Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.5 <**
Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.7 <**
Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric>=V3.1.5 <**
Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric>=V3.1.7 <**
Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.5 <**
Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.7 <**

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux, Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP.
  2. 2Review the reported fix. Update Linux/Linux to faa6ea32797a1847790514ff0da1be1d09771580; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to * if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Apr 13, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 15, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Jul 14, 2026

Sources and claim methodology

  • Source referencecert-portal.siemens.com
  • Source referencecert-portal.siemens.com
  • Source referencecert-portal.siemens.com
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-908
Source
CVE List V5
Source checked
Nov 4, 2026
References
11 linked sources
Open source record