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CVE-2021-23339

21
FAUCET Score

CVE-2021-23339 is a medium-severity vulnerability affecting Lightbend Akka HTTP versions prior to 10.1.14 and between 10.2.0 and 10.2.4, allowing multiple Transfer-Encoding headers. With a CVSS score of 6.5, it presents a network-based attack vector with low complexity, potentially leading to limited confidentiality and integrity impacts. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 10.1.14CPE matchmatch criteria
cpe:2.3:a:lightbend:akka-http:*:*:*:*:*:*:*:*
>= 10.2.0, < 10.2.4CPE matchmatch criteria
cpe:2.3:a:lightbend:akka-http:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.0MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
1.6
Impact Score
3.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.70%
Probability of exploitation in next 30 days
EPSS Percentile
49.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0070 is in the 31st percentile among its peer group of 23,723 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

mavenpatch availablevia ghsa
Product: com.typesafe.akka:akka-http-coreFixed in: 10.2.4
mavenpatch availablevia ghsa
Product: com.typesafe.akka:akka-http-coreFixed in: 10.1.14

Vendor Advisories (1)

mavenGHSA-2w7w-2j92-44hxmedium

HTTP Request Smuggling in akka-http-core

May 10, 2021

References

github.com / akka/akka-http/pull/3754%23issuecomment-779265201
Broken Link
snyk.io / vuln/SNYK-JAVA-COMTYPESAFEAKKA-1075043
Broken Link