{"id":"CVE-2026-49263","state":"PUBLISHED","title":"Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization","description":"Capstone is a disassembly framework. Prior to version 6.0.0-Alpha9, Capstone's WebAssembly backend accepts attacker-controlled raw WASM instruction bytes through the public `cs_disasm()` and `cs_disasm_iter()` APIs. For a large but well-formed `br_table` instruction, the WASM decoder accumulates the immediate length in a wider local variable but returns it through a `uint16_t` instruction-size path. When the encoded instruction length is exactly 65,536 bytes, the size wraps to zero and `cs_disasm()` can repeatedly decode the same instruction without advancing. For larger lengths, `cs_disasm_iter()` advances into the middle of the `br_table` payload and decodes target bytes as subsequent instructions. This is an availability and parser-integrity issue. Version 6.0.0-Alpha9 patches the issue.","publishedAt":"2026-08-14T17:49:36.804Z","updatedAt":"2026-08-17T19:52:03.982Z","severity":{"score":2,"label":"Low","version":"4.0","vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["capstone-engine capstone"],"affected":[{"vendor":"capstone-engine","product":"capstone","versions":[{"version":"< 6.0.0-Alpha9","status":"affected"}]}],"references":["https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr","https://github.com/capstone-engine/capstone/blob/251c5bb4bc9bb92973e738ae3c5f4ef86f103356/ChangeLog#L102"],"weaknesses":["CWE-197"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/49xxx/CVE-2026-49263.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-49263","state":"PUBLISHED","datePublished":"2026-08-14T17:49:36.804Z","dateUpdated":"2026-08-17T19:52:03.982Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-28T14:33:01.180Z"},"containers":{"cna":{"title":"Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization","descriptions":[{"lang":"en","value":"Capstone is a disassembly framework. Prior to version 6.0.0-Alpha9, Capstone's WebAssembly backend accepts attacker-controlled raw WASM instruction bytes through the public `cs_disasm()` and `cs_disasm_iter()` APIs. For a large but well-formed `br_table` instruction, the WASM decoder accumulates the immediate length in a wider local variable but returns it through a `uint16_t` instruction-size path. When the encoded instruction length is exactly 65,536 bytes, the size wraps to zero and `cs_disasm()` can repeatedly decode the same instruction without advancing. For larger lengths, `cs_disasm_iter()` advances into the middle of the `br_table` payload and decodes target bytes as subsequent instructions. This is an availability and parser-integrity issue. Version 6.0.0-Alpha9 patches the issue."}],"affected":[{"vendor":"capstone-engine","product":"capstone","versions":[{"version":"< 6.0.0-Alpha9","status":"affected"}]}],"references":[{"url":"https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr","name":"https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/capstone-engine/capstone/blob/251c5bb4bc9bb92973e738ae3c5f4ef86f103356/ChangeLog#L102","name":"https://github.com/capstone-engine/capstone/blob/251c5bb4bc9bb92973e738ae3c5f4ef86f103356/ChangeLog#L102","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":2,"baseSeverity":"LOW","vectorString":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-197","lang":"en","description":"CWE-197: Numeric Truncation Error","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-14T17:49:36.804Z"},"source":{"advisory":"GHSA-5m9f-vqcm-g5pr","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-17T19:51:57.796655Z","id":"CVE-2026-49263","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-17T19:52:03.982Z"}}]}}}