{"dataType": "CVE_RECORD", "cveMetadata": {"state": "PUBLISHED", "cveId": "CVE-2026-34877", "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca", "assignerShortName": "mitre", "dateUpdated": "2026-04-02T17:52:53.594Z", "dateReserved": "2026-03-31T00:00:00.000Z", "datePublished": "2026-04-02T00:00:00.000Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca", "shortName": "mitre", "dateUpdated": "2026-04-02T16:37:49.459Z"}, "descriptions": [{"lang": "en", "value": "An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs."}], "affected": [{"vendor": "n/a", "product": "n/a", "versions": [{"version": "n/a", "status": "affected"}]}], "references": [{"url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/"}, {"url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-serialized-data/"}], "problemTypes": [{"descriptions": [{"type": "text", "lang": "en", "description": "n/a"}]}]}, "adp": [{"problemTypes": [{"descriptions": [{"type": "CWE", "cweId": "CWE-250", "lang": "en", "description": "CWE-250 Execution with Unnecessary Privileges"}]}, {"descriptions": [{"type": "CWE", "cweId": "CWE-502", "lang": "en", "description": "CWE-502 Deserialization of Untrusted Data"}]}], "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-04-02T17:51:48.970447Z", "id": "CVE-2026-34877", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-02T17:52:53.594Z"}}]}, "dataVersion": "5.2"}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs."}], "id": "CVE-2026-34877", "lastModified": "2026-04-02T18:16:34.143", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2026-04-02T17:16:26.927", "references": [{"source": "cve@mitre.org", "url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/"}, {"source": "cve@mitre.org", "url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-serialized-data/"}], "sourceIdentifier": "cve@mitre.org", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-250"}, {"lang": "en", "value": "CWE-502"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.19.0,3.6.5]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "4.0.0"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "n/a", "source": "cna", "vendor": "n/a"}, "product": "mbedtls", "vendor": "mbed"}], "analysis": {"en": {"generated_at": "2026-04-02T22:37:50.065844+00:00", "value": {"mitigation_remediation": ["Upgrade Mbed TLS to a version that includes the CVE-2026-34877 fix.", "If an upgrade is delayed, isolate the affected application from the network until a patch is applied.", "Ensure the application does not serialize or persist SSL context structures externally.", "Monitor the system for signs of memory corruption or unexpected crashes.", "Apply any vendor-specified security hardening guidelines while waiting for a patch."], "summary": {"action": "Immediate Patch", "impact": "Arbitrary Code Execution"}, "threat_synthesis": {"affected_systems": "Mbed TLS, versions 2.19.0 through 3.6.5 and the 4.0.0 release, are impacted. The issue appears in the core TLS library and may affect any application that uses that version of the library.", "description_and_impact": "The vulnerability stems from insufficient protection of serialized SSL context or session structures. An attacker who can modify these serialized strings can trigger memory corruption that leads to arbitrary code execution. The weakness originates from incorrect use of privileged APIs, allowing exploitation of the encryption library\u2019s serialization routines.", "risk_and_exploitability": "The CVSS score of 9.8 places this vulnerability in the critical range. While the EPSS score is unavailable and the vulnerability is not listed in the KEV catalog, the high severity indicates significant risk. Based on the description, the likely attack vector involves an attacker who can inject or alter serialized SSL context data, possibly via the network or a compromised storage medium, leading to execution of privileged code paths within the library and full compromise of the vulnerable process."}}}}, "created": "2026-04-03T08:58:19.704458+00:00", "title": "Arbitrary Code Execution via Deserialization of SSL Context in Mbed TLS", "updated": "2026-04-03T09:18:59.342979+00:00", "vendors": ["mbed", "mbed$PRODUCT$mbedtls"]}