{"id":"CVE-2026-5187","state":"PUBLISHED","title":"Heap Out-of-Bounds Write in DecodeObjectId() in wolfSSL","description":"Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.","publishedAt":"2026-04-09T19:45:39.937Z","updatedAt":"2026-04-14T14:04:53.585Z","severity":{"score":2.3,"label":"Low","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N","source":"wolfSSL"},"assigner":"wolfSSL","products":["wolfSSL wolfSSL"],"affected":[{"vendor":"wolfSSL","product":"wolfSSL","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"5.9.0","versionType":"semver"}],"modules":["wolfcrypt/src/asn.c"],"programFiles":["wolfcrypt/src/asn.c"]}],"references":["https://github.com/wolfSSL/wolfssl"],"weaknesses":["CWE-122","CWE-787"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/5xxx/CVE-2026-5187.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-5187","state":"PUBLISHED","datePublished":"2026-04-09T19:45:39.937Z","dateUpdated":"2026-04-14T14:04:53.585Z","assignerShortName":"wolfSSL","assignerOrgId":"50d2cd11-d01a-48ed-9441-5bfce9d63b27","dateReserved":"2026-03-30T19:57:33.843Z"},"containers":{"cna":{"title":"Heap Out-of-Bounds Write in DecodeObjectId() in wolfSSL","descriptions":[{"lang":"en","value":"Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer."}],"affected":[{"vendor":"wolfSSL","product":"wolfSSL","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"5.9.0","versionType":"semver"}],"modules":["wolfcrypt/src/asn.c"],"programFiles":["wolfcrypt/src/asn.c"]}],"references":[{"url":"https://github.com/wolfSSL/wolfssl","name":"wolfSSL GitHub Repository"}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"LOW","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"LOW","baseScore":2.3,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-122","lang":"en","description":"CWE-122: Heap-based Buffer Overflow","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-787","lang":"en","description":"CWE-787: Out-of-bounds Write","type":"CWE"}]}],"providerMetadata":{"shortName":"wolfSSL","orgId":"50d2cd11-d01a-48ed-9441-5bfce9d63b27","dateUpdated":"2026-04-09T19:45:39.937Z"},"configurations":[{"lang":"en","value":"Bug 1 (off-by-one) affects any code calling DecodeObjectId() with an output buffer of size 1. Bug 2 (sizeof mismatch) is reachable via network when wolfSSL is compiled with HAVE_OID_DECODING or WOLFSSL_ASN_PRINT, and WC_ASN_UNKNOWN_EXT_CB is enabled with a registered unknown extension callback.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>Bug 1 (off-by-one) affects any code calling DecodeObjectId() with an output buffer of size 1. Bug 2 (sizeof mismatch) is reachable via network when wolfSSL is compiled with HAVE_OID_DECODING or WOLFSSL_ASN_PRINT, and WC_ASN_UNKNOWN_EXT_CB is enabled with a registered unknown extension callback.</p>"}]}],"workarounds":[{"lang":"en","value":"Do not enable WC_ASN_UNKNOWN_EXT_CB or do not register an unknown extension callback if not required. This mitigates the network-reachable variant (Bug 2) but does not address Bug 1.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>Do not enable WC_ASN_UNKNOWN_EXT_CB or do not register an unknown extension callback if not required. This mitigates the network-reachable variant (Bug 2) but does not address Bug 1.</p>"}]}],"solutions":[{"lang":"en","value":"Fix Bug 1: Add a bounds check requiring at least 2 output slots before writing the first OID arc split (y == 0 case). Fix Bug 2: Change callers to pass the element count (MAX_OID_SZ) instead of sizeof(decOid) as the output buffer size parameter.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>Fix Bug 1: Add a bounds check requiring at least 2 output slots before writing the first OID arc split (y == 0 case). Fix Bug 2: Change callers to pass the element count (MAX_OID_SZ) instead of sizeof(decOid) as the output buffer size parameter.</p>"}]}],"credits":[{"lang":"en","value":"ytsun, Independent Security Researcher","type":"finder"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 1.0.1"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-5187","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-04-14T14:03:11.195034Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-14T14:04:53.585Z"}}]}}}