Incorrect Failure Handling in RSA KEM RSASVE Encapsulation

Summary

Issue summary: Applications using RSASVE key encapsulation to establish a secret encryption key can send contents of an uninitialized memory buffer to a malicious peer. Impact summary: The uninitialized buffer might contain sensitive data from the previous execution of the application process which leads to sensitive data leakage to an attacker. RSA_public_encrypt() returns the number of bytes written on success and -1 on error. The affected code tests only whether the return value is non-zero. As a result, if RSA encryption fails, encapsulation can still return success to the caller, set the output lengths, and leave the caller to use the contents of the ciphertext buffer as if a valid KEM ciphertext had been produced. If applications use EVP_PKEY_encapsulate() with RSA/RSASVE on an attacker-supplied invalid RSA public key without first validating that key, then this may cause stale or uninitialized contents of the caller-provided ciphertext buffer to be disclosed to the attacker in place of the KEM ciphertext. As a workaround calling EVP_PKEY_public_check() or EVP_PKEY_public_check_quick() before EVP_PKEY_encapsulate() will mitigate the issue. The FIPS modules in 3.6, 3.5, 3.4, 3.3, 3.1 and 3.0 are affected by this issue.

Timeline

1. Apr 7, 2026, 10:00 PM UTCCVE published
2. Apr 8, 2026, 2:32 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. May 12, 2026, 12:09 PM UTCRecord last updated

Affected versions

• OpenSSL OpenSSL

  From 3.6.0 · fixed in 3.6.2; From 3.5.0 · fixed in 3.5.6; From 3.4.0 · fixed in 3.4.5; From 3.3.0 · fixed in 3.3.7; From 3.0.0 · fixed in 3.0.20

References 6