{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-33753", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-03-23T18:30:14.125Z", "datePublished": "2026-04-08T14:54:59.704Z", "dateUpdated": "2026-04-08T16:12:57.796Z"}, "containers": {"cna": {"title": "Improper Certificate Validation in rfc3161-client", "problemTypes": [{"descriptions": [{"cweId": "CWE-295", "lang": "en", "description": "CWE-295: Improper Certificate Validation", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "NONE", "baseScore": 6.2, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-3xxc-pwj6-jgrj", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-3xxc-pwj6-jgrj"}], "affected": [{"vendor": "trailofbits", "product": "rfc3161-client", "versions": [{"version": "< 1.0.6", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-04-08T14:54:59.704Z"}, "descriptions": [{"lang": "en", "value": "rfc3161-client is a Python library implementing the Time-Stamp Protocol (TSP) described in RFC 3161. Prior to 1.0.6, an Authorization Bypass vulnerability in rfc3161-client's signature verification allows any attacker to impersonate a trusted TimeStamping Authority (TSA). By exploiting a logic flaw in how the library extracts the leaf certificate from an unordered PKCS#7 bag of certificates, an attacker can append a spoofed certificate matching the target common_name and Extended Key Usage (EKU) requirements. This tricks the library into verifying these authorization rules against the forged certificate while validating the cryptographic signature against an actual trusted TSA (such as FreeTSA), thereby bypassing the intended TSA authorization pinning entirely. This vulnerability is fixed in 1.0.6."}], "source": {"advisory": "GHSA-3xxc-pwj6-jgrj", "discovery": "UNKNOWN"}}, "adp": [{"references": [{"url": "https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-3xxc-pwj6-jgrj", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-04-08T16:08:28.007589Z", "id": "CVE-2026-33753", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-08T16:12:57.796Z"}}]}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "rfc3161-client is a Python library implementing the Time-Stamp Protocol (TSP) described in RFC 3161. Prior to 1.0.6, an Authorization Bypass vulnerability in rfc3161-client's signature verification allows any attacker to impersonate a trusted TimeStamping Authority (TSA). By exploiting a logic flaw in how the library extracts the leaf certificate from an unordered PKCS#7 bag of certificates, an attacker can append a spoofed certificate matching the target common_name and Extended Key Usage (EKU) requirements. This tricks the library into verifying these authorization rules against the forged certificate while validating the cryptographic signature against an actual trusted TSA (such as FreeTSA), thereby bypassing the intended TSA authorization pinning entirely. This vulnerability is fixed in 1.0.6."}], "id": "CVE-2026-33753", "lastModified": "2026-04-08T17:21:19.367", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "NONE", "baseScore": 6.2, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.5, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-04-08T16:16:23.670", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-3xxc-pwj6-jgrj"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-3xxc-pwj6-jgrj"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-295"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

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{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.0.6)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "cna", "scores": [{"score": 100.0, "source": "cna"}]}, "original": {"product": "rfc3161-client", "source": "cna", "vendor": "trailofbits"}, "product": "rfc3161-client", "vendor": "trailofbits"}], "analysis": {"en": {"generated_at": "2026-04-08T16:20:31.374227+00:00", "value": {"mitigation_remediation": ["Upgrade rfc3161-client to version 1.0.6 or newer"], "summary": {"action": "Immediate Patch", "impact": "TSA impersonation via authorization bypass"}, "threat_synthesis": {"affected_systems": "The vulnerability affects the rfc3161-client library distributed by trailofbits. Any installation of rfc3161-client prior to version 1.0.6 is susceptible. No additional product or version specifics are provided beyond the 1.0.6 release threshold.", "description_and_impact": "A logic flaw in rfc3161-client's extraction of the leaf certificate from an unordered PKCS#7 bag allows an attacker to forge a certificate that matches the required common name and Extended Key Usage attributes. The library then verifies the authorization rules against the forged certificate while still validating the cryptographic signature against a legitimate trusted TimeStamping Authority. This bypasses the intended TSA authorization pinning and enables an attacker to impersonate a trusted TSA, potentially creating or claiming forged timestamps.", "risk_and_exploitability": "With a CVSS score of 6.2 the weakness presents a moderate severity risk. EPSS data is not available and the vulnerability is not listed in the CISA KEV catalog, indicating a lower public exploitation footprint. The attack likely requires control over the PKCS#7 signature input, allowing an attacker to inject a crafted certificate chain that satisfies the TSA verification logic. Once the forged certificate is accepted, an attacker can forge timestamps that appear valid to downstream consumers of the timestamp service."}}}}, "created": "2026-04-08T19:26:51.215205+00:00", "updated": "2026-04-08T19:39:09.083094+00:00", "vendors": ["trailofbits", "trailofbits$PRODUCT$rfc3161-client"]}