{"id":"CVE-2026-35188","state":"PUBLISHED","title":"Double-free When Checking OCSP Stapled Response","description":"Issue summary: A malicious server can exploit TLS OCSP stapling by delivering\na crafted response through the status_request extension, triggering a\ndouble-free in the client's certificate verification path.\n\nImpact summary: Successful exploitation allows an attacker to corrupt heap\nmemory via a double-free, potentially leading to a Denial of Service or\npossibly an attacker controlled code execution or other undefined behavior.\n\nIf OCSP stapling is enabled and the TLS client connects to a malicious server,\na crafted OCSP stapled response can trigger a double free in the TLS client\nwhen the stapled response is checked.\n\nThe OCSP stapling is not enabled by default. Reliable code execution\nthrough a double-free is technically complex and highly environment-dependent\nbut the Denial of Service impact is straightforward to achieve, warranting\nModerate severity.\n\nNo FIPS modules are affected by this issue as the affected code is outside\nthe OpenSSL FIPS module boundary.","publishedAt":"2026-06-09T16:03:24.395Z","updatedAt":"2026-06-10T20:02:41.587Z","severity":{"score":5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L","source":"CISA-ADP"},"assigner":"openssl","products":["OpenSSL OpenSSL"],"affected":[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","status":"affected","lessThan":"4.0.1","versionType":"semver"},{"version":"3.6.0","status":"affected","lessThan":"3.6.3","versionType":"semver"}]}],"references":["https://openssl-library.org/news/secadv/20260609.txt","https://github.com/openssl/openssl/commit/78d0154cffda03aaaac63a087cc523a6b35fa8fd","https://github.com/openssl/openssl/commit/131145d25659e8749a9ed1afb383484854cffb78"],"weaknesses":["CWE-415"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/35xxx/CVE-2026-35188.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-35188","state":"PUBLISHED","datePublished":"2026-06-09T16:03:24.395Z","dateUpdated":"2026-06-10T20:02:41.587Z","assignerShortName":"openssl","assignerOrgId":"3a12439a-ef3a-4c79-92e6-6081a721f1e5","dateReserved":"2026-04-01T17:36:26.323Z"},"containers":{"cna":{"title":"Double-free When Checking OCSP Stapled Response","descriptions":[{"lang":"en","value":"Issue summary: A malicious server can exploit TLS OCSP stapling by delivering\na crafted response through the status_request extension, triggering a\ndouble-free in the client's certificate verification path.\n\nImpact summary: Successful exploitation allows an attacker to corrupt heap\nmemory via a double-free, potentially leading to a Denial of Service or\npossibly an attacker controlled code execution or other undefined behavior.\n\nIf OCSP stapling is enabled and the TLS client connects to a malicious server,\na crafted OCSP stapled response can trigger a double free in the TLS client\nwhen the stapled response is checked.\n\nThe OCSP stapling is not enabled by default. Reliable code execution\nthrough a double-free is technically complex and highly environment-dependent\nbut the Denial of Service impact is straightforward to achieve, warranting\nModerate severity.\n\nNo FIPS modules are affected by this issue as the affected code is outside\nthe OpenSSL FIPS module boundary."}],"affected":[{"vendor":"OpenSSL","product":"OpenSSL","defaultStatus":"unaffected","versions":[{"version":"4.0.0","status":"affected","lessThan":"4.0.1","versionType":"semver"},{"version":"3.6.0","status":"affected","lessThan":"3.6.3","versionType":"semver"}]}],"references":[{"url":"https://openssl-library.org/news/secadv/20260609.txt","name":"OpenSSL Advisory","tags":["vendor-advisory"]},{"url":"https://github.com/openssl/openssl/commit/78d0154cffda03aaaac63a087cc523a6b35fa8fd","name":"4.0.1 git commit","tags":["patch"]},{"url":"https://github.com/openssl/openssl/commit/131145d25659e8749a9ed1afb383484854cffb78","name":"3.6.3 git commit","tags":["patch"]}],"metrics":[{"format":"other","other":{"content":{"text":"Moderate"},"type":"https://openssl-library.org/policies/general/security-policy/"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-415","description":"CWE-415 Double Free","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"openssl","orgId":"3a12439a-ef3a-4c79-92e6-6081a721f1e5","dateUpdated":"2026-06-10T07:47:57.674Z"},"credits":[{"lang":"en","type":"reporter","value":"Wang Kenaz (University of Illinois)"},{"lang":"en","type":"reporter","value":"Guido Vranken (Aisle Research)"},{"lang":"en","type":"reporter","value":"Aaron Grattafiori (Nvidia)"},{"lang":"en","type":"remediation developer","value":"Daniel Kubec"}],"datePublic":"2026-06-09T14:00:00.000Z","source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5,"attackVector":"NETWORK","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L","integrityImpact":"LOW","userInteraction":"NONE","attackComplexity":"HIGH","availabilityImpact":"LOW","privilegesRequired":"LOW","confidentialityImpact":"LOW"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-06-10T03:59:37.106557Z","id":"CVE-2026-35188","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-10T20:02:41.587Z"}}]}}}