{"id":"CVE-2026-28434","state":"PUBLISHED","title":"cpp-httplib's default exception handler leaks e.what() to clients via EXCEPTION_WHAT response header","description":"cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.35.0, when a request handler throws a C++ exception and the application has not registered a custom exception handler via set_exception_handler(), the library catches the exception and writes its message directly into the HTTP response as a header named EXCEPTION_WHAT. This header is sent to whoever made the request, with no authentication check and no special configuration required to trigger it. The behavior is on by default. A developer who does not know to opt in to set_exception_handler() will ship a server that leaks internal exception messages to any client. This vulnerability is fixed in 0.35.0.","publishedAt":"2026-03-04T19:34:30.486Z","updatedAt":"2026-03-04T20:55:40.320Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["yhirose cpp-httplib"],"affected":[{"vendor":"yhirose","product":"cpp-httplib","versions":[{"version":"< 0.35.0","status":"affected"}]}],"references":["https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-8mpw-r4gc-xm7q","https://github.com/yhirose/cpp-httplib/commit/defd907c7469c5c8281247b73bbd07be24c31164"],"weaknesses":["CWE-200"],"ingestedAt":"2026-10-29T20:11:31.369Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/28xxx/CVE-2026-28434.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-28434","state":"PUBLISHED","datePublished":"2026-03-04T19:34:30.486Z","dateUpdated":"2026-03-04T20:55:40.320Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-02-27T15:54:05.138Z"},"containers":{"cna":{"title":"cpp-httplib's default exception handler leaks e.what() to clients via EXCEPTION_WHAT response header","descriptions":[{"lang":"en","value":"cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.35.0, when a request handler throws a C++ exception and the application has not registered a custom exception handler via set_exception_handler(), the library catches the exception and writes its message directly into the HTTP response as a header named EXCEPTION_WHAT. This header is sent to whoever made the request, with no authentication check and no special configuration required to trigger it. The behavior is on by default. A developer who does not know to opt in to set_exception_handler() will ship a server that leaks internal exception messages to any client. This vulnerability is fixed in 0.35.0."}],"affected":[{"vendor":"yhirose","product":"cpp-httplib","versions":[{"version":"< 0.35.0","status":"affected"}]}],"references":[{"url":"https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-8mpw-r4gc-xm7q","name":"https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-8mpw-r4gc-xm7q","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/yhirose/cpp-httplib/commit/defd907c7469c5c8281247b73bbd07be24c31164","name":"https://github.com/yhirose/cpp-httplib/commit/defd907c7469c5c8281247b73bbd07be24c31164","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-200","lang":"en","description":"CWE-200: Exposure of Sensitive Information to an Unauthorized Actor","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-03-04T19:34:30.486Z"},"source":{"advisory":"GHSA-8mpw-r4gc-xm7q","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-04T20:45:05.207964Z","id":"CVE-2026-28434","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-03-04T20:55:40.320Z"}}]}}}