CVE-2026-34874

// Generated PoC code for demonstration #include <mbedtls/x509_crt.h> int main() { // Setup Mbed TLS context mbedtls_x509_crt crt; mbedtls_x509_crt_init(&crt); // Malformed data triggering NULL pointer dereference in DN parsing // Note: Actual byte sequence depends on specific parsing logic unsigned char malformed_data[] = { 0x30, 0x82, 0x01, 0x00, ... }; // Trigger parsing int ret = mbedtls_x509_crt_parse(&crt, malformed_data, sizeof(malformed_data)); // If vulnerable, the program crashes writing to address 0 mbedtls_x509_crt_free(&crt); return 0; }

{"cve": {"id": "CVE-2026-34874", "sourceIdentifier": "[email protected]", "published": "2026-04-01T19:16:33.390", "lastModified": "2026-04-03T20:06:34.877", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "An issue was discovered in Mbed TLS through 3.6.5 and 4.x through 4.0.0. There is a NULL pointer dereference in distinguished name parsing that allows an attacker to write to address 0."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:arm:mbed_tls:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5.0", "versionEndExcluding": "3.6.6", "matchCriteriaId": "3278BC57-7535-4FB5-B2AA-2938CB48504B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:arm:mbed_tls:4.0.0:*:*:*:*:*:*:*", "matchCriteriaId": "8EF688FA-732F-4EAF-BAC6-AC3CDAF19588"}]}]}], "references": [{"url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-null-pointer-dereference-x509/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}