What’s Vulnerable › Vulnerabilities

CVE-2020-12457

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-08-21 · updated 2026-06-17
• Weakness: CWE-835

Description

An issue was discovered in wolfSSL before 4.5.0. It mishandles the change_cipher_spec (CCS) message processing logic for TLS 1.3. If an attacker sends ChangeCipherSpec messages in a crafted way involving more than one in a row, the server becomes stuck in the ProcessReply() loop, i.e., a denial of service.

Affected products

• wolfSSL: before 4.5.0 — fixed in 4.5.0

How to fix

Upgrade to a fixed version: wolfSSL 4.5.0. Check the vendor advisory for mitigations.

References

• https://github.com/wolfSSL/wolfssl/pull/2927
• https://github.com/wolfSSL/wolfssl/releases/tag/v4.5.0-stable
• https://github.com/wolfSSL/wolfssl/pull/2927
• https://github.com/wolfSSL/wolfssl/releases/tag/v4.5.0-stable

Get alerted when CVE-2020-12457 or the next vulnerability affects your stack