CVE-2021-42697: Akka HTTP Server

High severity, CVSS 7.5. EPSS: 36.1% chance of exploitation in the next 30 days.

Akka HTTP 10.1.x before 10.1.15 and 10.2.x before 10.2.7 can encounter stack exhaustion while parsing HTTP headers, which allows a remote attacker to conduct a Denial of Service attack by sending a User-Agent header with deeply nested comments.

Affected products

• Akka HTTP Server: from 10.1.0, before 10.1.15 (fixed in 10.1.15); from 10.2.0, before 10.2.7 (fixed in 10.2.7)

Published 2021-11-02. Last modified 2026-06-17.