{"id":"CVE-2026-47775","state":"PUBLISHED","title":"Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, the OAuth2 HTTP filter's encrypt()/decrypt() functions use AES-256-CBC without an authentication tag (no HMAC, no AEAD). The /callback endpoint returns HTTP 302 on successful decryption and HTTP 401 on padding failure, creating a padding oracle. An attacker who obtains the encrypted CodeVerifier cookie can recover the plaintext PKCE code_verifier in ~6,200 requests (~100 seconds), then exchange it with a stolen authorization code to obtain the victim's access token. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.","publishedAt":"2026-06-26T17:23:51.663Z","updatedAt":"2026-06-29T15:20:39.815Z","severity":{"score":6.8,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["envoyproxy envoy"],"affected":[{"vendor":"envoyproxy","product":"envoy","versions":[{"version":">= 1.38.0, < 1.38.1","status":"affected"},{"version":">= 1.37.0, < 1.37.3","status":"affected"},{"version":">= 1.36.0, < 1.36.7","status":"affected"},{"version":"< 1.35.11","status":"affected"}]}],"references":["https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p"],"weaknesses":["CWE-209","CWE-327"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/47xxx/CVE-2026-47775.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-47775","state":"PUBLISHED","datePublished":"2026-06-26T17:23:51.663Z","dateUpdated":"2026-06-29T15:20:39.815Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-19T22:36:16.882Z"},"containers":{"cna":{"title":"Envoy OAuth2 Filter: Padding Oracle via AES-256-CBC Cookie Decryption","descriptions":[{"lang":"en","value":"Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, the OAuth2 HTTP filter's encrypt()/decrypt() functions use AES-256-CBC without an authentication tag (no HMAC, no AEAD). The /callback endpoint returns HTTP 302 on successful decryption and HTTP 401 on padding failure, creating a padding oracle. An attacker who obtains the encrypted CodeVerifier cookie can recover the plaintext PKCE code_verifier in ~6,200 requests (~100 seconds), then exchange it with a stolen authorization code to obtain the victim's access token. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1."}],"affected":[{"vendor":"envoyproxy","product":"envoy","versions":[{"version":">= 1.38.0, < 1.38.1","status":"affected"},{"version":">= 1.37.0, < 1.37.3","status":"affected"},{"version":">= 1.36.0, < 1.36.7","status":"affected"},{"version":"< 1.35.11","status":"affected"}]}],"references":[{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p","name":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.8,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-209","lang":"en","description":"CWE-209: Generation of Error Message Containing Sensitive Information","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-327","lang":"en","description":"CWE-327: Use of a Broken or Risky Cryptographic Algorithm","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-26T17:23:51.663Z"},"source":{"advisory":"GHSA-396h-jpq4-vc7p","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-396h-jpq4-vc7p","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-29T15:05:22.645121Z","id":"CVE-2026-47775","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-29T15:20:39.815Z"}}]}}}