CVE-2024-34702: Botan has a Denial of Service Due to Excessive Name Constraints

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-08 · 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 3.5.0 and 2.19.5, checking name constraints in X.509 certificates is quadratic in the number of names and name constraints. An attacker who presented a certificate chain which contained a very large number of names in the SubjectAlternativeName, signed by a CA certificate which contained a large number of name constraints, could cause a denial of service. The problem has been addressed in Botan 3.5.0 and a partial backport has also been applied and is included in Botan 2.19.5.

Affected products

randombit Botan: from 3.0.0 before 3.5.0; before 2.19.5 — fixed in 2.19.5, 3.5.0

How to fix

Upgrade to a fixed version: randombit Botan 2.19.5, 3.5.0. Check the vendor advisory for mitigations.

References

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