{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-5500", "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "state": "PUBLISHED", "assignerShortName": "wolfSSL", "dateReserved": "2026-04-03T15:33:05.734Z", "datePublished": "2026-04-10T03:10:25.671Z", "dateUpdated": "2026-04-10T03:10:25.671Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "shortName": "wolfSSL", "dateUpdated": "2026-04-10T03:10:25.671Z"}, "title": "Improper Validation of AES-GCM Authentication Tag Length in PKCS#7 Envelope Allows Authentication Bypass", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-20", "description": "CWE-20 Improper input validation", "type": "CWE"}]}], "affected": [{"vendor": "wolfSSL", "product": "wolfSSL", "modules": ["wc_PKCS7_DecodeAuthEnvelopedData"], "programFiles": ["wolfcrypt/src/pkcs7.c"], "versions": [{"status": "affected", "version": "0", "lessThanOrEqual": "5.9.0", "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "wolfSSL's wc_PKCS7_DecodeAuthEnvelopedData() does not properly sanitize the AES-GCM authentication tag length received and has no lower bounds check. A man-in-the-middle can therefore truncate the mac field from 16 bytes to 1 byte, reducing the tag check from 2\u207b\u00b9\u00b2\u2078 to 2\u207b\u2078.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "wolfSSL's wc_PKCS7_DecodeAuthEnvelopedData() does not properly sanitize the AES-GCM authentication tag length received and has no lower bounds check. A man-in-the-middle can therefore truncate the mac field from 16 bytes to 1 byte, reducing the tag check from 2\u207b\u00b9\u00b2\u2078 to 2\u207b\u2078."}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl/pull/10102"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "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": "HIGH", "baseScore": 8.7, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}}], "credits": [{"lang": "en", "value": "Calif.io in collaboration with Claude and Anthropic Research", "type": "finder"}], "source": {"discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.1"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "wolfSSL's wc_PKCS7_DecodeAuthEnvelopedData() does not properly sanitize the AES-GCM authentication tag length received and has no lower bounds check. A man-in-the-middle can therefore truncate the mac field from 16 bytes to 1 byte, reducing the tag check from 2\u207b\u00b9\u00b2\u2078 to 2\u207b\u2078."}], "id": "CVE-2026-5500", "lastModified": "2026-04-10T04:17:17.080", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.7, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "facts@wolfssl.com", "type": "Secondary"}]}, "published": "2026-04-10T04:17:17.080", "references": [{"source": "facts@wolfssl.com", "url": "https://github.com/wolfSSL/wolfssl/pull/10102"}], "sourceIdentifier": "facts@wolfssl.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-20"}], "source": "facts@wolfssl.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,5.9.0]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "wolfSSL", "source": "cna", "vendor": "wolfSSL"}, "product": "wolfssl", "vendor": "wolfssl"}], "analysis": {"en": {"generated_at": "2026-04-10T04:21:14.768819+00:00", "value": {"mitigation_remediation": ["Apply the latest wolfSSL patch that addresses the tag length check, as referenced in PR\u00a010102", "If an update is not yet possible, avoid accepting PKCS#7 enveloped data from untrusted sources or implement a manual tag length verification routine before decryption", "Monitor traffic and logs for anomalies that could indicate an attempt to truncate authentication tags"], "summary": {"action": "Immediate Patch", "impact": "Authentication Bypass via AES\u2011GCM tag truncation"}, "threat_synthesis": {"affected_systems": "wolfSSL software that implements the PKCS#7 envelope decoding routine is affected. The specific version is not listed, so any release that includes the vulnerable wc_PKCS7_DecodeAuthEnvelopedData implementation may be impacted.", "description_and_impact": "The flaw resides in wc_PKCS7_DecodeAuthEnvelopedData, which omits a lower bound check on the AES\u2011GCM authentication tag length. An attacker can truncate the MAC field from the proper 16 bytes to 1 byte, reducing the tag verification probability from 2\u207b\u00b9\u00b2\u2078 to 2\u207b\u2078 and allowing the encrypted data to be processed without authenticating it. This constitutes a bypass of the integrity check and enables unauthorized disclosure of encrypted secrets.", "risk_and_exploitability": "The CVSS score of 8.7 indicates high severity. Although exact EPSS data is unavailable, the vulnerability involves a known denial of verification and is not listed in CISA's KEV catalogue, suggesting it is not yet widely exploited. The likely attack vector is a man\u2011in\u2011the\u2011middle positioned on the channel carrying PKCS#7 enveloped data, capable of truncating the MAC field. Because the bug removes a critical integrity check, successful exploitation would give an attacker unauthorized access to the decrypted payload."}}}}, "created": "2026-04-10T08:35:53.574344+00:00", "updated": "2026-04-10T09:26:55.310335+00:00", "vendors": ["wolfssl", "wolfssl$PRODUCT$wolfssl"]}