{"id":"CVE-2026-43186","state":"PUBLISHED","title":"ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()\n\nOn the receive path, __ioam6_fill_trace_data() uses trace->nodelen\nto decide how much data to write for each node. It trusts this field\nas-is from the incoming packet, with no consistency check against\ntrace->type (the 24-bit field that tells which data items are\npresent). A crafted packet can set nodelen=0 while setting type bits\n0-21, causing the function to write ~100 bytes past the allocated\nregion (into skb_shared_info), which corrupts adjacent heap memory\nand leads to a kernel panic.\n\nAdd a shared helper ioam6_trace_compute_nodelen() in ioam6.c to\nderive the expected nodelen from the type field, and use it:\n\n  - in ioam6_iptunnel.c (send path, existing validation) to replace\n    the open-coded computation;\n  - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose\n    nodelen is inconsistent with the type field, before any data is\n    written.\n\nPer RFC 9197, bits 12-21 are each short (4-octet) fields, so they\nare included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to\n0xff1ffc00).","publishedAt":"2026-05-06T11:27:57.053Z","updatedAt":"2026-10-19T19:16:23.065Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"f4d9d4b8fd839719d564651671e24c62c545c23b","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"fb3c662fafebc5b9d74417ed1de8759f6bb72143","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"632d233cf2e64a46865ae2c064ae3c9df7c8864f","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"0591d6509c2ff13f09ea2998434aba0c0472e978","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"e90346a2f1e8917d5760a44a1f61c44e3b36d96b","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"ea3632aefc04205436868541638e26f4a74d5637","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"6db8b56eed62baacaf37486e83378a72635c04cc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/ioam6.h","net/ipv6/exthdrs.c","net/ipv6/ioam6.c","net/ipv6/ioam6_iptunnel.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"5.15.202","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.165","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.128","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","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":["include/net/ioam6.h","net/ipv6/exthdrs.c","net/ipv6/ioam6.c","net/ipv6/ioam6_iptunnel.c"]}],"references":["https://git.kernel.org/stable/c/f4d9d4b8fd839719d564651671e24c62c545c23b","https://git.kernel.org/stable/c/fb3c662fafebc5b9d74417ed1de8759f6bb72143","https://git.kernel.org/stable/c/632d233cf2e64a46865ae2c064ae3c9df7c8864f","https://git.kernel.org/stable/c/0591d6509c2ff13f09ea2998434aba0c0472e978","https://git.kernel.org/stable/c/e90346a2f1e8917d5760a44a1f61c44e3b36d96b","https://git.kernel.org/stable/c/ea3632aefc04205436868541638e26f4a74d5637","https://git.kernel.org/stable/c/6db8b56eed62baacaf37486e83378a72635c04cc"],"weaknesses":["CWE-122"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43186.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43186","state":"PUBLISHED","datePublished":"2026-05-06T11:27:57.053Z","dateUpdated":"2026-10-19T19:16:23.065Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:55.991Z"},"containers":{"cna":{"title":"ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()\n\nOn the receive path, __ioam6_fill_trace_data() uses trace->nodelen\nto decide how much data to write for each node. It trusts this field\nas-is from the incoming packet, with no consistency check against\ntrace->type (the 24-bit field that tells which data items are\npresent). A crafted packet can set nodelen=0 while setting type bits\n0-21, causing the function to write ~100 bytes past the allocated\nregion (into skb_shared_info), which corrupts adjacent heap memory\nand leads to a kernel panic.\n\nAdd a shared helper ioam6_trace_compute_nodelen() in ioam6.c to\nderive the expected nodelen from the type field, and use it:\n\n  - in ioam6_iptunnel.c (send path, existing validation) to replace\n    the open-coded computation;\n  - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose\n    nodelen is inconsistent with the type field, before any data is\n    written.\n\nPer RFC 9197, bits 12-21 are each short (4-octet) fields, so they\nare included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to\n0xff1ffc00)."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"f4d9d4b8fd839719d564651671e24c62c545c23b","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"fb3c662fafebc5b9d74417ed1de8759f6bb72143","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"632d233cf2e64a46865ae2c064ae3c9df7c8864f","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"0591d6509c2ff13f09ea2998434aba0c0472e978","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"e90346a2f1e8917d5760a44a1f61c44e3b36d96b","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"ea3632aefc04205436868541638e26f4a74d5637","versionType":"git"},{"version":"9ee11f0fff205b4b3df9750bff5e94f97c71b6a0","status":"affected","lessThan":"6db8b56eed62baacaf37486e83378a72635c04cc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/ioam6.h","net/ipv6/exthdrs.c","net/ipv6/ioam6.c","net/ipv6/ioam6_iptunnel.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"5.15.202","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.165","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.128","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","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":["include/net/ioam6.h","net/ipv6/exthdrs.c","net/ipv6/ioam6.c","net/ipv6/ioam6_iptunnel.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f4d9d4b8fd839719d564651671e24c62c545c23b"},{"url":"https://git.kernel.org/stable/c/fb3c662fafebc5b9d74417ed1de8759f6bb72143"},{"url":"https://git.kernel.org/stable/c/632d233cf2e64a46865ae2c064ae3c9df7c8864f"},{"url":"https://git.kernel.org/stable/c/0591d6509c2ff13f09ea2998434aba0c0472e978"},{"url":"https://git.kernel.org/stable/c/e90346a2f1e8917d5760a44a1f61c44e3b36d96b"},{"url":"https://git.kernel.org/stable/c/ea3632aefc04205436868541638e26f4a74d5637"},{"url":"https://git.kernel.org/stable/c/6db8b56eed62baacaf37486e83378a72635c04cc"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable code is reached while processing received IPv6 Hop-by-Hop IOAM options in the network stack. A remote packet sender can craft the IOAM trace header for an IOAM-enabled target.\nAC:L - Exploitation requires a malformed but straightforward IOAM Pre-allocated Trace option with inconsistent nodelen and type fields. There is no race or attacker-uncontrolled timing condition once IOAM is enabled on the target interface.\nPR:N - The packet processing path has no authentication or per-sender privilege check before calling the vulnerable fill routine. Although enabling IOAM and creating namespaces is administrative setup, a remote attacker against such a deployment needs no privileges.\nUI:N - No victim user action is needed. The vulnerable path runs automatically when the kernel receives and parses the crafted IPv6 packet.\nS:U - The corruption occurs inside the same kernel security authority that processes the packet. This is not a VM escape or other cross-scope boundary bypass.\nC:H - The bug is a kernel heap out-of-bounds write into adjacent skb memory, including skb_shared_info in the described case. Such memory corruption can be leveraged for kernel memory disclosure as part of exploitation.\nI:H - This is an out-of-bounds kernel heap write controlled by attacker-supplied packet fields and layout choices. Kernel heap corruption is defensibly exploitable for arbitrary modification or code execution.\nA:H - The fix commit states the corruption leads to a kernel panic, and malformed packets can be sent repeatedly. Kernel panic or crash is high availability impact."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:26:24.342Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"5.15.202"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.1.165"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.6.128"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.12.75"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.18.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.19.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-43186","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:15:25.722836Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-122","lang":"en","type":"CWE","description":"CWE-122 Heap-based Buffer Overflow"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:16:23.065Z"}}]}}}