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netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-31427

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-31427

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "faa6ea32797a1847790514ff0da1be1d09771580",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "82baeb871e8f04906bc886273fdf0209e1754eb3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "6e5e3c87b7e6212f1d8414fc2e4d158b01e12025",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "7edca70751b9bdb5b83eed53cde21eccf3c86147",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "01f34a80ac23ae90b1909b94b4ed05343a62f646",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "52fdda318ef2362fc5936385bcb8b3d0328ee629",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab9e64e5e3c0516577818804aaf13a630d67bc9",
        "lessThan": "6a2b724460cb67caed500c508c2ae5cf012e4db4",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/netfilter/nf_conntrack_sip.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "2.6.26"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "2.6.26",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.253",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.203",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.168",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.131",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.80",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.21",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.11",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/netfilter/nf_conntrack_sip.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-31427

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#28275 · Revision 1
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Publisher date
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