{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43233","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-05-01T14:12:55.995Z","datePublished":"2026-05-06T11:28:29.565Z","dateUpdated":"2026-08-05T12:26:46.159Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:26:46.159Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_h323: fix OOB read in decode_choice()\n\nIn decode_choice(), the boundary check before get_len() uses the\nvariable `len`, which is still 0 from its initialization at the top of\nthe function:\n\n    unsigned int type, ext, len = 0;\n    ...\n    if (ext || (son->attr & OPEN)) {\n        BYTE_ALIGN(bs);\n        if (nf_h323_error_boundary(bs, len, 0))  /* len is 0 here */\n            return H323_ERROR_BOUND;\n        len = get_len(bs);                        /* OOB read */\n\nWhen the bitstream is exactly consumed (bs->cur == bs->end), the check\nnf_h323_error_boundary(bs, 0, 0) evaluates to (bs->cur + 0 > bs->end),\nwhich is false.  The subsequent get_len() call then dereferences\n*bs->cur++, reading 1 byte past the end of the buffer.  If that byte\nhas bit 7 set, get_len() reads a second byte as well.\n\nThis can be triggered remotely by sending a crafted Q.931 SETUP message\nwith a User-User Information Element containing exactly 2 bytes of\nPER-encoded data ({0x08, 0x00}) to port 1720 through a firewall with\nthe nf_conntrack_h323 helper active.  The decoder fully consumes the\nPER buffer before reaching this code path, resulting in a 1-2 byte\nheap-buffer-overflow read confirmed by AddressSanitizer.\n\nFix this by checking for 2 bytes (the maximum that get_len() may read)\ninstead of the uninitialized `len`.  This matches the pattern used at\nevery other get_len() call site in the same file, where the caller\nchecks for 2 bytes of available data before calling get_len()."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","baseScore":8.2,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable H.323 conntrack Q.931 helper processes TCP/1720 network traffic, and the fix explicitly documents remote triggering with a crafted Q.931 SETUP User-User IE through a firewall with the helper active.\nAC:L - The trigger is a deterministic malformed PER buffer of exact length; no race, heap grooming, or victim-controlled timing is required beyond the helper being active.\nPR:N - The attacker only sends network packets to a system/firewall where the H.323 helper is configured; the Q.931 parsing path has no authentication or attacker privilege check.\nUI:N - No victim user action is needed once the helper is active; packet receipt alone drives conntrack into the decoder.\nS:U - The impact remains within the kernel/network filtering security authority and does not cross a VM, IOMMU, or other separate security boundary.\nC:L - The bug performs a strictly bounded 1-2 byte out-of-bounds heap read via get_len(), so any confidentiality impact is limited rather than arbitrary memory disclosure.\nI:N - The vulnerable operation is read-only, and the subsequent bounds check returns an error; there is no out-of-bounds write or structure corruption.\nA:H - The remotely triggerable kernel heap out-of-bounds read is reachable repeatedly from packet processing and can cause sanitizer/oops/panic-style kernel failure on affected deployments."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_h323_asn1.c"],"versions":[{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041","status":"affected","versionType":"git"},{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a","status":"affected","versionType":"git"},{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"81f2fc5b0d0cf4696146f00f837596d10b92dead","status":"affected","versionType":"git"},{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"7ef82863d42261817a6394c6c881bd6757a70f16","status":"affected","versionType":"git"},{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"53d32735d77ab56cc3fc7bd53a7d099418f19be1","status":"affected","versionType":"git"},{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"f0a83d0a4b7c127d32ac06d607a9214937716129","status":"affected","versionType":"git"},{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"35f1943d242e1b9f0b6e91c0c93bfb293a9f8224","status":"affected","versionType":"git"},{"version":"ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa","lessThan":"baed0d9ba91d4f390da12d5039128ee897253d60","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_conntrack_h323_asn1.c"],"versions":[{"version":"4.15","status":"affected"},{"version":"0","lessThan":"4.15","status":"unaffected","versionType":"semver"},{"version":"5.10.252","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.202","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.165","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.128","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.75","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.16","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"6.19.6","lessThanOrEqual":"6.19.*","status":"unaffected","versionType":"semver"},{"version":"7.0","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.10.252"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.15.202"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.1.165"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.6.128"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.12.75"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.18.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.19.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"7.0"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041"},{"url":"https://git.kernel.org/stable/c/2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a"},{"url":"https://git.kernel.org/stable/c/81f2fc5b0d0cf4696146f00f837596d10b92dead"},{"url":"https://git.kernel.org/stable/c/7ef82863d42261817a6394c6c881bd6757a70f16"},{"url":"https://git.kernel.org/stable/c/53d32735d77ab56cc3fc7bd53a7d099418f19be1"},{"url":"https://git.kernel.org/stable/c/f0a83d0a4b7c127d32ac06d607a9214937716129"},{"url":"https://git.kernel.org/stable/c/35f1943d242e1b9f0b6e91c0c93bfb293a9f8224"},{"url":"https://git.kernel.org/stable/c/baed0d9ba91d4f390da12d5039128ee897253d60"}],"title":"netfilter: nf_conntrack_h323: fix OOB read in decode_choice()","x_generator":{"engine":"bippy-1.2.0"}}}}