CVE-2026-118767
MediumCVSS 4.8Exploitation Probability (EPSS)
Low risk12th percentile - higher than 12% of all known CVEs
Summary
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.
Risk Assessment
An attacker could bypass the application's password policy by supplying a password with an embedded NUL character. This may weaken authentication mechanisms based on bcrypt in the Python binding.
Recommendation
Update Botan to version 3.13.0 or later. Review applications using bcrypt via the Python binding for NUL character validation in passwords.
Other vulnerabilities in Botan
See all- CVE-2015-7825High
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.
- CVE-2015-7824High
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.
- CVE-2016-2850High
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.
- CVE-2016-2849High
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.
- CVE-2016-2194High
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.
- CVE-2015-7827High
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.
- CVE-2015-5727High
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.
- CVE-2015-5726High
The BER decoder in Botan versions 0.10.x before 1.10.10 and 1.11.x before 1.11.19 allows remote attackers to cause an application crash via an empty BIT STRING in ASN.1 data.
- CVE-2014-9742High
The Miller-Rabin primality check in Botan before 1.10.8 and 1.11.x before 1.11.9 improperly uses a single random base, making it easier for remote attackers to defeat cryptographic protection mechanisms via a DH group.
- CVE-2026-118769Critical
In the Botan C++ cryptography library, the C API function botan_block_cipher_block_size converted a size_t block size to int without a bounds check. In an application that accepts external algorithm parameter strings and uses FFI raw ECB mode, an attacker can select the variable-block-size Lion cipher, causing the reported size to be truncated, insufficient memory allocation, and later memory corruption. The issue is fixed in version 3.13.0.
Original NVD description (English source)
Botan is a C++ cryptography library. From 1.11.22 until 3.13.0, Botan's 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. This issue is fixed in version 3.13.0.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS