Security readout for executives and security teams
Plain-English summary
Akka HTTP applications using vulnerable akka-http-core versions may mishandle requests with multiple Transfer-Encoding headers. In certain deployments, this can let a request be interpreted differently by front-end and back-end systems, creating HTTP request smuggling risk.
Executive priority
Treat this as a focused dependency remediation item, not a broad emergency. Prioritize public-facing Akka HTTP services and systems behind complex proxy chains, then patch through normal release controls.
Technical view
CVE-2021-23339 affects com.typesafe.akka:akka-http-core before 10.1.14 and 10.2.0 through 10.2.4. The reported flaw allows multiple Transfer-Encoding headers, a parsing condition associated with HTTP request smuggling. CVSS 3.1 is 5.0 with network attack vector and high attack complexity.
Likely exposure
Exposure is likely limited to Java/Scala services that directly or transitively include vulnerable akka-http-core versions and process HTTP traffic. Internet-facing services, gateways, or services behind reverse proxies deserve priority review.
Exploitation context
The provided bundle does not show active exploitation, and KEV is false. CVSS lists high attack complexity and user interaction, so practical risk likely depends on specific HTTP routing, proxy, and back-end parsing behavior.
Researcher notes
The sources identify the vulnerable package and version ranges but provide limited operational detail. Avoid assuming exploitability without confirming deployed Akka HTTP usage, traffic exposure, and intermediaries that could parse ambiguous Transfer-Encoding behavior differently.
Mitigation direction
- Upgrade akka-http-core to a version outside the affected ranges.
- For 10.1.x, use 10.1.14 or later where compatible.
- For 10.2.x, move beyond 10.2.4 where compatible.
- Review Snyk and Akka guidance before release.
- Prioritize internet-facing Akka HTTP services first.
Validation and detection
- Check SBOMs and dependency trees for com.typesafe.akka:akka-http-core.
- Identify applications processing HTTP traffic with affected versions.
- Confirm whether vulnerable versions are deployed in production images.
- Review reverse proxy and gateway paths in front of Akka HTTP services.
- Verify patched dependency versions after rebuild and deployment.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-23339 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L1.63.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://snyk.io/vuln/SNYK-JAVA-COMTYPESAFEAKKA-1075043CVE reference · x_refsource_MISC
- https://github.com/akka/akka-http/pull/3754%23issuecomment-779265201CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.