{"id":"CVE-2026-74569","title":"netfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()\n\nsip_help_tcp() stores the size change of each NAT-rewritten SIP message\nin s16 diff and a…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < ed1f9be6dc8e2e280b8725e44ccdc6e0cd38640d","Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < 1b0843f9e9b9b0b9b4b70d143b67e58163c85b2c","Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < 32d4abc8923b0d4046fd63ad6e4917872e44eb6d","Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < 63eea41759fd682229c14e0a2205802b46d106f3","Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < c97621a110e386b2dd69e276eb699e1d3cec581d","Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < f74554e67ccf04d1fa71069e8c9afa2717e40716","Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < ef5e2c6555d2bb52dfe0e4053a8c6193f9d83b64","Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < db3d0e0e5d4bc5ab4fe445b9f413d1b486508ca5","Linux 2.6.34"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T19:00:29.648445Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:05:56.675Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74569","references":[{"url":"https://git.kernel.org/stable/c/ed1f9be6dc8e2e280b8725e44ccdc6e0cd38640d"},{"url":"https://git.kernel.org/stable/c/1b0843f9e9b9b0b9b4b70d143b67e58163c85b2c"},{"url":"https://git.kernel.org/stable/c/32d4abc8923b0d4046fd63ad6e4917872e44eb6d"},{"url":"https://git.kernel.org/stable/c/63eea41759fd682229c14e0a2205802b46d106f3"},{"url":"https://git.kernel.org/stable/c/c97621a110e386b2dd69e276eb699e1d3cec581d"},{"url":"https://git.kernel.org/stable/c/f74554e67ccf04d1fa71069e8c9afa2717e40716"},{"url":"https://git.kernel.org/stable/c/ef5e2c6555d2bb52dfe0e4053a8c6193f9d83b64"},{"url":"https://git.kernel.org/stable/c/db3d0e0e5d4bc5ab4fe445b9f413d1b486508ca5"}],"tags":["cve.org"],"epss":0.00388,"epssPercentile":0.31282,"ingestedAt":"2026-10-16T19:46:24.341Z","slug":"CVE-2026-74569","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()\n\nsip_help_tcp() stores the size change of each NAT-rewritten SIP message\nin s16 diff and accumulates it in s16 tdiff, but a single message can\ngrow by more than S16_MAX while the packet stays under the 65535\nenlarge_skb() limit: nf_nat_sip() rewrites every matching URI, and a long\nContact list expands the message by tens of kilobytes. diff then wraps,\nand \"datalen = datalen + diff - msglen\" yields a huge unsigned datalen,\nso the next iteration's ct_sip_get_header() reads past the linearized skb\ntail.\n\nWiden diff, tdiff and the seq_adjust hook to s32. Both are bounded by the\n65535 byte packet limit, and the seqadj core is already s32\n(nf_ct_seqadj_set() takes s32), so no previously accepted input is\nrejected.\n\n  BUG: KASAN: use-after-free in ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464)\n  Read of size 1 at addr ffff888010800000 by task ksoftirqd/1/25\n   ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464)\n   sip_help_tcp (net/netfilter/nf_conntrack_sip.c:1694)\n   nf_confirm (net/netfilter/nf_conntrack_proto.c:183)\n   nf_hook_slow (net/netfilter/core.c:619)\n   ip6_output (net/ipv6/ip6_output.c:246)\n   ip6_forward (net/ipv6/ip6_output.c:690)\n   ipv6_rcv (net/ipv6/ip6_input.c:351)\n   __netif_receive_skb_one_core (net/core/dev.c:6212)\n   process_backlog (net/core/dev.c:6676)\n   __napi_poll (net/core/dev.c:7735)\n   net_rx_action (net/core/dev.c:7955)\n   handle_softirqs (kernel/softirq.c:622)\n   run_ksoftirqd (kernel/softirq.c:1076)\n   ...\n\n## Affected\n\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < ed1f9be6dc8e2e280b8725e44ccdc6e0cd38640d`\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < 1b0843f9e9b9b0b9b4b70d143b67e58163c85b2c`\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < 32d4abc8923b0d4046fd63ad6e4917872e44eb6d`\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < 63eea41759fd682229c14e0a2205802b46d106f3`\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < c97621a110e386b2dd69e276eb699e1d3cec581d`\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < f74554e67ccf04d1fa71069e8c9afa2717e40716`\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < ef5e2c6555d2bb52dfe0e4053a8c6193f9d83b64`\n- `Linux >= f5b321bd37fbec9188feb1f721ab46a5ac0b35da < db3d0e0e5d4bc5ab4fe445b9f413d1b486508ca5`\n- `Linux 2.6.34`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}