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 attacker to conduct a Denial of Service attack by sending a User-Agent header with deeply nested comments.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 36.1%, higher than 98% of all known CVEs. Patch or mitigate before the next change window.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 36.14% probability · 98th percentile
- Public exploits
- 1 in Exploit-DB · first 11 May 2022
- CISA KEV
- Not listed
- Weakness
- CWE-674
- Affected
- akka/http server
- Source
- cve@mitre.org
EPSS 36.1% since 3 November 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://packetstormsecurity.com/files/167018/Akka-HTTP-10.1.14-Denial-Of-Service.htmlExploit, Third Party Advisory, VDB Entry
- https://akka.io/blog/Vendor Advisory
- https://akka.io/blog/news/2021/11/02/akka-http-10.2.7-releasedRelease Notes, Vendor Advisory
- https://akka.io/blog/news/2021/11/22/akka-http-10.1.15-releasedRelease Notes, Vendor Advisory
- https://doc.akka.io/docs/akka-http/current/security/2021-CVE-2021-42697-stack-overflow-parsing-user-agent.htmlVendor Advisory
- http://packetstormsecurity.com/files/167018/Akka-HTTP-10.1.14-Denial-Of-Service.htmlExploit, Third Party Advisory, VDB Entry
- https://akka.io/blog/Vendor Advisory
- https://akka.io/blog/news/2021/11/02/akka-http-10.2.7-releasedRelease Notes, Vendor Advisory
- https://akka.io/blog/news/2021/11/22/akka-http-10.1.15-releasedRelease Notes, Vendor Advisory
- https://doc.akka.io/docs/akka-http/current/security/2021-CVE-2021-42697-stack-overflow-parsing-user-agent.htmlVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.