CVE-2024-34703: Botan Vulnerable to Denial of Service Due to Overly Large Elliptic Curve Parameters

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-06-30 · updated 2026-06-17
Weakness: CWE-405

Description

Botan is a C++ cryptography library. X.509 certificates can identify elliptic curves using either an object identifier or using explicit encoding of the parameters. Prior to versions 3.3.0 and 2.19.4, an attacker could present an ECDSA X.509 certificate using explicit encoding where the parameters are very large. The proof of concept used a 16Kbit prime for this purpose. When parsing, the parameter is checked to be prime, causing excessive computation. This was patched in 2.19.4 and 3.3.0 to allow the prime parameter of the elliptic curve to be at most 521 bits. No known workarounds are available. Note that support for explicit encoding of elliptic curve parameters is deprecated in Botan.

Affected products

randombit Botan: from 3.30 before 3.3.1; before 2.19.4 — fixed in 2.19.4, 3.3.1

How to fix

Upgrade to a fixed version: randombit Botan 2.19.4, 3.3.1. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2024-34703 or the next vulnerability affects your stack