CVE-2026-72253 (GCVE-0-2026-72253)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-23 12:47
VLAI
Title
netfilter: nf_conntrack_sip: validate skb_dst() before accessing it
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: validate skb_dst() before accessing it tc ingress and openvswitch do not guarantee routing information to be available. These subsystems use the conntrack helper infrastructure, and the SIP helper relies on the skb_dst() to be present if sip_external_media is set to 1 (which is disabled by default as a module parameter). This effectively disables the sip_external_media toggle for these subsystems without resulting in a crash.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < 7866116a040b3a23fb094e7d8f7ea3d61b3ac70b (git)
Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < c5ef7228be04518d95591fc5369a9c554b19756d (git)
Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < 0aec339694a56e263d4b22475ff7211d40900830 (git)
Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < e64a48c50a1ff565a98c6a98d82b5b942868e76e (git)
Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < c199ed687c00841daf60e9d131976958583a8c09 (git)
Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < 09755dc62b026076b1d47f83489eb0547c8135e0 (git)
Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < b843a96252f672332837ea2ecb7c8db0acf68e20 (git)
Affected: cae3a2627520c3795b54533c5328b77af3405dbe , < e5e24a365a5e024efef63cc49abb345fbd4852c5 (git)
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Linux Linux Affected: 4.3
Unaffected: 0 , < 4.3 (semver)
Unaffected: 5.10.266 , ≤ 5.10.* (semver)
Unaffected: 5.15.217 , ≤ 5.15.* (semver)
Unaffected: 6.1.184 , ≤ 6.1.* (semver)
Unaffected: 6.6.148 , ≤ 6.6.* (semver)
Unaffected: 6.12.101 , ≤ 6.12.* (semver)
Unaffected: 6.18.42 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conntrack_sip.c"
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: validate skb_dst() before accessing it\n\ntc ingress and openvswitch do not guarantee routing information to be\navailable. These subsystems use the conntrack helper infrastructure, and\nthe SIP helper relies on the skb_dst() to be present if\nsip_external_media is set to 1 (which is disabled by default as a module\nparameter).\n\nThis effectively disables the sip_external_media toggle for these\nsubsystems without resulting in a crash."
        }
      ],
      "metrics": [
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            "version": "3.1"
          },
          "scenarios": [
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              "value": "AV:N - Remote attackers reach set_expected_rtp_rtcp() by sending crafted SIP/SDP (e.g., INVITE) through Open vSwitch or tc ingress ct(helper=sip) on internet-facing VoIP SBC/NFV gateways where packets are conntrack-processed before skb_dst routing metadata is attached.\nAC:L - Once sip_external_media=1, sip_direct_media=0, and the SIP helper are configured on OVS/tc ingress, the attacker fully controls SIP/SDP contents to reach the skb_dst(skb)-\u003edev dereference without races or conditions outside their control.\nPR:N - Exploitation requires no privileges on the victim host; a remote SIP peer only needs to deliver malicious signaling to an already-configured OVS/tc SIP ALG with sip_external_media enabled, with no authentication or local access.\nUI:N - No victim user interaction is required; the kernel SIP helper parses attacker-supplied SIP/SDP during conntrack processing in softirq without any user action beyond normal automated packet handling.\nS:U - A NULL pointer dereference in nf_conntrack_sip causes a kernel oops/panic within the same kernel security domain on the gateway; it does not cross VM, IOMMU, or sandbox boundaries.\nC:N - The failure is a direct NULL pointer dereference from skb_dst(skb) being NULL on tc/OVS ingress paths; there is no use-after-free, out-of-bounds read, or other memory disclosure primitive.\nI:N - Accessing skb_dst(skb)-\u003edev when skb_dst is NULL cannot modify memory or hijack control flow beyond the immediate fault; CVSS guidance assigns None for pure NULL-deref crashes without write capability.\nA:H - The invalid skb_dst dereference in set_expected_rtp_rtcp() during SIP SDP processing causes a kernel oops/panic-class fault, denying availability on the VoIP gateway until reboot; the crash is reliably reproducible with crafted SIP traffic."
            }
          ]
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72253",
    "datePublished": "2026-08-15T05:54:41.490Z",
    "dateReserved": "2026-08-09T03:40:39.915Z",
    "dateUpdated": "2026-08-23T12:47:08.038Z",
    "state": "PUBLISHED"
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      "date": "2026-09-23",
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: validate skb_dst() before accessing it\n\ntc ingress and openvswitch do not guarantee routing information to be\navailable. These subsystems use the conntrack helper infrastructure, and\nthe SIP helper relies on the skb_dst() to be present if\nsip_external_media is set to 1 (which is disabled by default as a module\nparameter).\n\nThis effectively disables the sip_external_media toggle for these\nsubsystems without resulting in a crash."
          }
        ],
        "id": "CVE-2026-72253",
        "lastModified": "2026-08-23T13:16:42.497",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-08-15T06:21:52.760",
        "references": [
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            "url": "https://git.kernel.org/stable/c/09755dc62b026076b1d47f83489eb0547c8135e0"
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            "url": "https://git.kernel.org/stable/c/0aec339694a56e263d4b22475ff7211d40900830"
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          },
          {
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            "url": "https://git.kernel.org/stable/c/e5e24a365a5e024efef63cc49abb345fbd4852c5"
          },
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/e64a48c50a1ff565a98c6a98d82b5b942868e76e"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-18T17:59:30+00:00",
      "cve": "CVE-2026-72253",
      "id": "CVE-2026-72253",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: nf_conntrack_sip: validate skb_dst() before accessing it",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72253.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-31T16:26:21Z",
      "cve": "CVE-2026-72253",
      "id": "CVE-2026-72253",
      "initial_release_date": "2026-08-31T16:26:21Z",
      "product_status:known_affected": "317",
      "product_status:known_not_affected": "45",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72253",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72253.json",
      "version": "2"
    }
  }
}



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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.