{"id":"CVE-2026-23457","state":"PUBLISHED","title":"netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()\n\nsip_help_tcp() parses the SIP Content-Length header with\nsimple_strtoul(), which returns unsigned long, but stores the result in\nunsigned int clen.  On 64-bit systems, values exceeding UINT_MAX are\nsilently truncated before computing the SIP message boundary.\n\nFor example, Content-Length 4294967328 (2^32 + 32) is truncated to 32,\ncausing the parser to miscalculate where the current message ends.  The\nloop then treats trailing data in the TCP segment as a second SIP\nmessage and processes it through the SDP parser.\n\nFix this by changing clen to unsigned long to match the return type of\nsimple_strtoul(), and reject Content-Length values that exceed the\nremaining TCP payload length.","publishedAt":"2026-04-03T15:15:38.193Z","updatedAt":"2026-10-19T18:35:44.867Z","severity":{"score":8.6,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"ed81b6a7012485acdb9c6c80735a0b7d8e5e1873","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"b75209debb9adab287b3caa982f77788c1e15027","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"528b4509c9dfc272e2e92d811915e5211650d383","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"75fcaee5170e7dbbee778927134ef2e9568b4659","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"865dba58958c3a86786f89a501971ab0e3ec6ba9","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"d4f17256544cc37f6534a14a27a9dec3540c2015","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"fbce58e719a17aa215c724473fd5baaa4a8dc57c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_sip.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.34","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.34","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.20","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.10","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_sip.c"]}],"references":["https://git.kernel.org/stable/c/ed81b6a7012485acdb9c6c80735a0b7d8e5e1873","https://git.kernel.org/stable/c/cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f","https://git.kernel.org/stable/c/b75209debb9adab287b3caa982f77788c1e15027","https://git.kernel.org/stable/c/528b4509c9dfc272e2e92d811915e5211650d383","https://git.kernel.org/stable/c/75fcaee5170e7dbbee778927134ef2e9568b4659","https://git.kernel.org/stable/c/865dba58958c3a86786f89a501971ab0e3ec6ba9","https://git.kernel.org/stable/c/d4f17256544cc37f6534a14a27a9dec3540c2015","https://git.kernel.org/stable/c/fbce58e719a17aa215c724473fd5baaa4a8dc57c","https://cert-portal.siemens.com/productcert/html/ssa-082556.html","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":["CWE-190"],"ingestedAt":"2026-10-29T20:11:21.040Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23457.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23457","state":"PUBLISHED","datePublished":"2026-04-03T15:15:38.193Z","dateUpdated":"2026-10-19T18:35:44.867Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:46.020Z"},"containers":{"cna":{"title":"netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()\n\nsip_help_tcp() parses the SIP Content-Length header with\nsimple_strtoul(), which returns unsigned long, but stores the result in\nunsigned int clen.  On 64-bit systems, values exceeding UINT_MAX are\nsilently truncated before computing the SIP message boundary.\n\nFor example, Content-Length 4294967328 (2^32 + 32) is truncated to 32,\ncausing the parser to miscalculate where the current message ends.  The\nloop then treats trailing data in the TCP segment as a second SIP\nmessage and processes it through the SDP parser.\n\nFix this by changing clen to unsigned long to match the return type of\nsimple_strtoul(), and reject Content-Length values that exceed the\nremaining TCP payload length."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"ed81b6a7012485acdb9c6c80735a0b7d8e5e1873","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"b75209debb9adab287b3caa982f77788c1e15027","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"528b4509c9dfc272e2e92d811915e5211650d383","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"75fcaee5170e7dbbee778927134ef2e9568b4659","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"865dba58958c3a86786f89a501971ab0e3ec6ba9","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"d4f17256544cc37f6534a14a27a9dec3540c2015","versionType":"git"},{"version":"f5b321bd37fbec9188feb1f721ab46a5ac0b35da","status":"affected","lessThan":"fbce58e719a17aa215c724473fd5baaa4a8dc57c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_sip.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.34","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.34","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.20","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.10","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_sip.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/ed81b6a7012485acdb9c6c80735a0b7d8e5e1873"},{"url":"https://git.kernel.org/stable/c/cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f"},{"url":"https://git.kernel.org/stable/c/b75209debb9adab287b3caa982f77788c1e15027"},{"url":"https://git.kernel.org/stable/c/528b4509c9dfc272e2e92d811915e5211650d383"},{"url":"https://git.kernel.org/stable/c/75fcaee5170e7dbbee778927134ef2e9568b4659"},{"url":"https://git.kernel.org/stable/c/865dba58958c3a86786f89a501971ab0e3ec6ba9"},{"url":"https://git.kernel.org/stable/c/d4f17256544cc37f6534a14a27a9dec3540c2015"},{"url":"https://git.kernel.org/stable/c/fbce58e719a17aa215c724473fd5baaa4a8dc57c"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","baseScore":8.6,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable parser is reached by TCP SIP packets processed by the in-kernel netfilter SIP conntrack helper on a firewall/NAT/SIP gateway. In a reasonable SIP ALG deployment, a remote peer can deliver the crafted SIP payload over the network.\nAC:L - The attacker controls the SIP TCP stream contents, including the oversized Content-Length and trailing data that is reinterpreted as another SIP/SDP message. No race or condition outside the attacker's control is required once the helper is active.\nPR:N - A remote SIP peer does not need local credentials or kernel privileges to send packets through an already configured SIP conntrack helper. Although local CAP_NET_ADMIN can configure helpers, the highest reasonable deployment is a network-facing SIP gateway where the attacker only sends traffic.\nUI:N - No victim user action is needed after the SIP helper is deployed. The crafted TCP payload is processed automatically on packet traversal.\nS:U - The affected logic is kernel netfilter conntrack/NAT state within the same security authority. This is not a VM escape, IOMMU bypass, or other cross-scope boundary break.\nC:L - The bug does not expose kernel memory, but smuggled SDP can create unintended SIP media expectations that may allow limited otherwise-blocked traffic to protected endpoints. That can expose limited traffic or service responses behind the firewall.\nI:L - The primary impact is limited integrity loss in conntrack/NAT policy state: attacker-controlled trailing bytes can be processed as a separate SIP/SDP message and create or alter expectations. This is not arbitrary kernel memory write or code execution.\nA:H - Crafted traffic can repeatedly drive incorrect SIP helper parsing, packet drops, NAT mangling, and expectation-state pollution for affected SIP flows. 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