CVE-2026-118766

In the Botan library, the botan ocsp_check command requested an OCSP response from a certificate's Authority Information Access URL without verifying the response signature or authorizing the signer. A malicious responder or on-path attacker could return a matching and timely GOOD response with an empty, invalid, or unauthorized signature, causing a revoked certificate to produce exit status 0 and OCSP check OK output. Only the command-line interface is affected; the issue is fixed in version 3.13.0.

In the Botan library, the Python binding converted Python strings containing U+0000 to const char* values without consistently rejecting the embedded NUL, causing bcrypt and check_bcrypt to process only the prefix before the NUL. Applications could validate a longer password but hash a shorter effective value, allowing application password-policy bypass; scrypt and argon2 are unaffected. The issue is fixed in version 3.13.0.

In the Botan C++ cryptography library, from 3.7.0 until 3.13.0, an application that calls AutoSeeded_RNG::clear() and then calls randomize with an empty output buffer while the generator is unseeded can cause AutoSeeded_RNG to mark itself seeded without consulting the configured entropy source. On builds without BOTAN_HAS_SYSTEM_RNG, the fallback uses only a clock value and process ID, so a later non-empty request can produce output from predictable state. This is fixed in version 3.13.0.

Botan before 1.11.22 improperly validates certificate paths, allowing remote attackers to cause a denial of service via a certificate with a loop in the certificate chain.

Botan versions 1.11.x before 1.11.22 are vulnerable to a padding-oracle attack that allows remote attackers to decrypt TLS ciphertext data using CBC ciphersuites.

Botan versions 1.11.x before 1.11.29 do not enforce TLS policy for signature algorithms and ECC curves, allowing remote attackers to conduct downgrade attacks.

Botan before 1.10.13 and 1.11.x before 1.11.29 do not use a constant-time algorithm to perform a modular inverse on the signature nonce k, which might allow remote attackers to obtain ECDSA secret keys via a timing side-channel attack.

The ressol function in Botan before 1.10.11 and 1.11.x before 1.11.27 allows remote attackers to cause a denial of service (infinite loop) via unspecified input to the OS2ECP function, related to a composite modulus.

Botan before 1.10.13 and 1.11.x before 1.11.22 makes it easier for remote attackers to conduct million-message attacks by measuring time differences related to decoding of PKCS#1 padding.

The BER decoder in Botan 1.10.x before 1.10.10 and 1.11.x before 1.11.19 allows remote attackers to cause a denial of service (memory consumption) via unspecified vectors, related to a length field.