{"id":"CVE-2026-63891","state":"PUBLISHED","title":"thunderbolt: property: Cap recursion depth in __tb_property_parse_dir()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Cap recursion depth in __tb_property_parse_dir()\n\nA DIRECTORY entry's value field is used as the dir_offset for a\nrecursive call into __tb_property_parse_dir() with no depth counter.\nA crafted peer that chains DIRECTORY entries into a back-reference\nloop drives the parser until the kernel stack is exhausted and the\nguard page fires.  Any untrusted XDomain peer (cable, dock, in-line\ninspector, adjacent host) that reaches the PROPERTIES_REQUEST\ncontrol-plane exchange can trigger this without authentication.\n\nThread a depth counter through tb_property_parse() and\n__tb_property_parse_dir(), and reject blocks that exceed\nTB_PROPERTY_MAX_DEPTH = 8.  That is comfortably larger than any\nobserved legitimate XDomain layout.\n\nOperators who do not need XDomain host-to-host discovery can disable\nthe path entirely with thunderbolt.xdomain=0 on the kernel command\nline.","publishedAt":"2026-07-19T14:55:02.840Z","updatedAt":"2026-07-19T14:55:02.840Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"2b5f47a710172c962ef42d1b732b04d2ad0dce21","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"95839a67ea56ca35732aad7f711404a3127cfe2d","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"0a84ab9271936c11e84e511bb52fc5682f8b6726","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"b4621e5ef63405c317a84b711faf3bd75b3c6a94","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"f31c6d220f455b5af63590302b30e1b932d14599","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"830c8a9b467e7d3a158483d37fa7dc13892b293a","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"ed9455ef4bd9babc90f92e526abe3fb68c1a8709","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"928abe19fbf0127003abcb1ea69cabc1c897d0ab","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/property.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.15","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/property.c"]}],"references":["https://git.kernel.org/stable/c/2b5f47a710172c962ef42d1b732b04d2ad0dce21","https://git.kernel.org/stable/c/95839a67ea56ca35732aad7f711404a3127cfe2d","https://git.kernel.org/stable/c/0a84ab9271936c11e84e511bb52fc5682f8b6726","https://git.kernel.org/stable/c/b4621e5ef63405c317a84b711faf3bd75b3c6a94","https://git.kernel.org/stable/c/f31c6d220f455b5af63590302b30e1b932d14599","https://git.kernel.org/stable/c/830c8a9b467e7d3a158483d37fa7dc13892b293a","https://git.kernel.org/stable/c/ed9455ef4bd9babc90f92e526abe3fb68c1a8709","https://git.kernel.org/stable/c/928abe19fbf0127003abcb1ea69cabc1c897d0ab"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63891.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63891","state":"PUBLISHED","datePublished":"2026-07-19T14:55:02.840Z","dateUpdated":"2026-07-19T14:55:02.840Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.019Z"},"containers":{"cna":{"title":"thunderbolt: property: Cap recursion depth in __tb_property_parse_dir()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Cap recursion depth in __tb_property_parse_dir()\n\nA DIRECTORY entry's value field is used as the dir_offset for a\nrecursive call into __tb_property_parse_dir() with no depth counter.\nA crafted peer that chains DIRECTORY entries into a back-reference\nloop drives the parser until the kernel stack is exhausted and the\nguard page fires.  Any untrusted XDomain peer (cable, dock, in-line\ninspector, adjacent host) that reaches the PROPERTIES_REQUEST\ncontrol-plane exchange can trigger this without authentication.\n\nThread a depth counter through tb_property_parse() and\n__tb_property_parse_dir(), and reject blocks that exceed\nTB_PROPERTY_MAX_DEPTH = 8.  That is comfortably larger than any\nobserved legitimate XDomain layout.\n\nOperators who do not need XDomain host-to-host discovery can disable\nthe path entirely with thunderbolt.xdomain=0 on the kernel command\nline."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"2b5f47a710172c962ef42d1b732b04d2ad0dce21","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"95839a67ea56ca35732aad7f711404a3127cfe2d","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"0a84ab9271936c11e84e511bb52fc5682f8b6726","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"b4621e5ef63405c317a84b711faf3bd75b3c6a94","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"f31c6d220f455b5af63590302b30e1b932d14599","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"830c8a9b467e7d3a158483d37fa7dc13892b293a","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"ed9455ef4bd9babc90f92e526abe3fb68c1a8709","versionType":"git"},{"version":"cdae7c07e3e3509eaabc18c1640a55dc5b99c179","status":"affected","lessThan":"928abe19fbf0127003abcb1ea69cabc1c897d0ab","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/property.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.15","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/property.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/2b5f47a710172c962ef42d1b732b04d2ad0dce21"},{"url":"https://git.kernel.org/stable/c/95839a67ea56ca35732aad7f711404a3127cfe2d"},{"url":"https://git.kernel.org/stable/c/0a84ab9271936c11e84e511bb52fc5682f8b6726"},{"url":"https://git.kernel.org/stable/c/b4621e5ef63405c317a84b711faf3bd75b3c6a94"},{"url":"https://git.kernel.org/stable/c/f31c6d220f455b5af63590302b30e1b932d14599"},{"url":"https://git.kernel.org/stable/c/830c8a9b467e7d3a158483d37fa7dc13892b293a"},{"url":"https://git.kernel.org/stable/c/ed9455ef4bd9babc90f92e526abe3fb68c1a8709"},{"url":"https://git.kernel.org/stable/c/928abe19fbf0127003abcb1ea69cabc1c897d0ab"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-07-19T14:55:02.840Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.10.259"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.12.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}