CVE-2021-42697HTTP Server Out-of-Bounds Write
Uncontrolled Recursion in Akka HTTP
Published May 24, 2022 · Updated Jul 9, 2026 · Also known as GHSA-3hw2-h67c-wq66
Key Facts
Patch immediately- CVE-2021-42697 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting HTTP Server (Akka), com.typesafe.akka:aakka-http-core_2.13.0-M3 (maven), com.typesafe.akka:akka-http-core_2.11 (maven) and 5 more products.
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 36% probability of exploitation in the next 30 days.
- Fixed versions are available, including HTTP Server 10.1.15, com.typesafe.akka:aakka-http-core_2.13.0-M3 10.1.15, com.typesafe.akka:akka-http-core_2.11 10.1.15.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Scores
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
36%
Higher than 98.4% of all scored CVEs
Exploit maturity
Proof of concept
ATLAS score
41/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Not listed
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Proof of concept
Public exploit code
1
Proof-of-concept links
In-the-wild evidence
0
Reports of active use
Advisories And Exploit References
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2021-42697
- advisoryhttps://akka.io/blog/
- advisoryGHSA advisory
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.
Affected Products
8 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| HTTP ServerAkka | See advisory | 10.1.15 |
| com.typesafe.akka:aakka-http-core_2.13.0-M3maven | >= 10.1.0 | 10.1.15 |
| com.typesafe.akka:akka-http-core_2.11maven | >= 10.1.0 | 10.1.15 |
| com.typesafe.akka:akka-http-core_2.12maven | >= 10.1.0 | 10.1.15 |
| com.typesafe.akka:akka-http-core_2.13maven | >= 10.1.0 | 10.1.15 |
Patched Releases
HTTP Server
10.1.15
com.typesafe.akka:aakka-http-core_2.13.0-M3
10.1.15
com.typesafe.akka:akka-http-core_2.11
10.1.15
com.typesafe.akka:akka-http-core_2.12
10.1.15, 10.2.7
com.typesafe.akka:akka-http-core_2.13
10.1.15, 10.2.7
com.typesafe.akka:akka-http-core_2.13.0-M5
10.1.15
com.typesafe.akka:akka-http-core_2.13.0-RC2
10.1.15
com.typesafe.akka:akka-http-core_2.13.0-RC3
10.1.15
Timeline
Publicly disclosed
May 24, 2022
Last updated
Jul 9, 2026
Weakness Type
- CWE-674 Uncontrolled Recursion
- CWE-787 Out-of-bounds Write
References
- advisorynvd.nist.gov · CVE-2021-42697
- advisoryakka.io · blog
- advisoryGHSA advisory
- exploitExploitDB-50892
- articledoc.akka.io · CVE-2021-42697
FAQ
Common Questions.
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: HTTP Server (Akka); com.typesafe.akka:aakka-http-core_2.13.0-M3 (maven) versions >= 10.1.0; com.typesafe.akka:akka-http-core_2.11 (maven) versions >= 10.1.0, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including HTTP Server 10.1.15, com.typesafe.akka:aakka-http-core_2.13.0-M3 10.1.15, com.typesafe.akka:akka-http-core_2.11 10.1.15.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
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