CVE-2026-54876

*** Pendiente de traducción *** Issue summary: A malicious TLS server can cause a memory leak in a TLS<br /> client that has enabled OCSP response checking by sending an OCSP<br /> response that contains no single response entries.<br /> <br /> Impact summary: An attacker can leak an attacker-tunable amount of memory<br /> per TLS handshake in a victim client application. A long-running client<br /> that repeatedly connects to a malicious server can have its memory<br /> exhausted, resulting in a Denial of Service.<br /> <br /> CWE: CWE-401: Missing Release of Memory after Effective Lifetime<br /> <br /> Description: The affected function is called during X.509 certificate<br /> chain verification when OCSP response checking is enabled<br /> with the X509_V_FLAG_OCSP_RESP_CHECK or X509_V_FLAG_OCSP_RESP_CHECK_ALL<br /> verification flags, for example when a TLS client verifies an OCSP<br /> response stapled into the TLS handshake by the server.<br /> <br /> When the received BasicOCSPResponse contains an empty SEQUENCE OF<br /> SingleResponse, which is permitted on the wire and accepted by the<br /> OpenSSL decoder, the OCSP_BASICRESP structure allocated by<br /> OCSP_response_get1_basic() was not freed because an early return<br /> bypassed the cleanup code at the end of the function.<br /> <br /> The amount of memory leaked per handshake can be amplified by the<br /> attacker by padding the certs field of the BasicOCSPResponse with<br /> bogus certificates, which are parsed and stored in the leaked<br /> structure before the empty response check triggers the early return.<br /> A long-running TLS client that repeatedly connects to a malicious<br /> server can have its memory exhausted over time.<br /> <br /> OCSP response checking is not enabled by default. Only client<br /> applications that explicitly enable the OCSP response check<br /> verification flags are affected.<br /> <br /> FIPS impact: no<br /> <br /> The FIPS modules in 4.0 and 3.6 are not affected by this issue as the<br /> affected code is outside the OpenSSL FIPS module boundary.