A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd->signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7->signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions.
"}],"value":"A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd->signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7->signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions."}],"impacts":[{"descriptions":[{"lang":"en","value":"Overflow Buffers"}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"LOCAL","baseScore":2.2,"baseSeverity":"LOW","exploitMaturity":"UNREPORTED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-121","description":"CWE-121: Stack-based Buffer Overflow","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-787","description":"CWE-787: Out-of-bounds Write","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-03-19T16:54:33.442Z","orgId":"50d2cd11-d01a-48ed-9441-5bfce9d63b27","shortName":"wolfSSL"},"references":[{"name":"GitHub Pull Request","url":"https://github.com/wolfSSL/wolfssl/pull/9630"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Update to the patched version of wolfSSL. The fix adds proper bounds checking in wc_PKCS7_BuildSignedAttributes() to validate that the number of custom signed attributes does not exceed the available space in the fixed-size signedAttribs array, returning BUFFER_E if the limit is exceeded.
"}],"value":"Update to the patched version of wolfSSL. The fix adds proper bounds checking in wc_PKCS7_BuildSignedAttributes() to validate that the number of custom signed attributes does not exceed the available space in the fixed-size signedAttribs array, returning BUFFER_E if the limit is exceeded."}],"source":{"discovery":"EXTERNAL"},"title":"Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Ensure that applications using wolfSSL PKCS7 signing functionality validate and limit the number of custom signed attributes (signedAttribsSz) to no more than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default signed attributes enabled. Do not allow untrusted input to control the signedAttribs array or its size.
"}],"value":"Ensure that applications using wolfSSL PKCS7 signing functionality validate and limit the number of custom signed attributes (signedAttribsSz) to no more than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default signed attributes enabled. Do not allow untrusted input to control the signedAttribs array or its size."}],"x_generator":{"engine":"Vulnogram 0.5.0"}}},"cveMetadata":{"assignerOrgId":"50d2cd11-d01a-48ed-9441-5bfce9d63b27","assignerShortName":"wolfSSL","cveId":"CVE-2026-0819","datePublished":"2026-03-19T16:54:33.442Z","dateReserved":"2026-01-09T17:04:43.340Z","dateUpdated":"2026-03-19T17:19:37.134Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-03-19 17:16:21","lastModifiedDate":"2026-04-29 18:50:05","problem_types":["CWE-121","CWE-787","CWE-121 CWE-121: Stack-based Buffer Overflow","CWE-787 CWE-787: Out-of-bounds Write"],"metrics":{"cvssMetricV40":[{"source":"facts@wolfssl.com","type":"Secondary","cvssData":{"version":"4.0","vectorString":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","baseScore":2.2,"baseSeverity":"LOW","attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"UNREPORTED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.2}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5.0","versionEndExcluding":"5.9.0","matchCriteriaId":"CC77D5AA-8CFE-43F8-8FD9-E003646125E0"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"819","Ordinal":"1","Title":"Stack buffer overflow in PKCS7 SignedData encoding with custom s","CVE":"CVE-2026-0819","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"819","Ordinal":"1","NoteData":"A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd->signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7->signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions.","Type":"Description","Title":"Stack buffer overflow in PKCS7 SignedData encoding with custom s"}]}}}