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CVE-2023-22465

Http4s has fatal error parsing User-Agent and Server headers

MEDIUM
5.3
CVSS Score
Published: January 4, 2023 at 03:30 PM UTC
Updated: June 17, 2026 at 05:35 AM UTC
2 products affected across 2 vendorsHTTP4SHTTP4S

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.9%
SSVC
PoC

Description

Http4s is a Scala interface for HTTP services. Starting with version 0.1.0 and prior to versions 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38, the `User-Agent` and `Server` header parsers are susceptible to a fatal error on certain inputs. In http4s, modeled headers are lazily parsed, so this only applies to services that explicitly request these typed headers. Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38. As a workaround, use the weakly typed header interface.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

HTTP4S· Typelevel
95%
0.1.0 ≤ v < 0.21.340.22.0 ≤ v < 0.22.150.23.0 ≤ v < 0.23.171.0.0 milestone11.0.0 milestone101.0.0 milestone111.0.0 milestone121.0.0 milestone131.0.0 milestone141.0.0 milestone151.0.0 milestone161.0.0 milestone171.0.0 milestone181.0.0 milestone191.0.0 milestone21.0.0 milestone201.0.0 milestone211.0.0 milestone221.0.0 milestone231.0.0 milestone241.0.0 milestone251.0.0 milestone261.0.0 milestone271.0.0 milestone281.0.0 milestone291.0.0 milestone31.0.0 milestone301.0.0 milestone311.0.0 milestone321.0.0 milestone331.0.0 milestone341.0.0 milestone351.0.0 milestone361.0.0 milestone371.0.0 milestone41.0.0 milestone51.0.0 milestone61.0.0 milestone71.0.0 milestone81.0.0 milestone9
Affected range stops below 0.21.34, so it looks safe — our inference, not a vendor statement
Affected range stops below 0.22.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 0.23.17, so it looks safe — our inference, not a vendor statement
HTTP4S· HTTP4Smaven
60%
v < 0.21.34v < 0.22.15v < 0.23.17v < 1.0.0-M38
Affected range stops below 0.21.34, so it looks safe — our inference, not a vendor statement
Affected range stops below 0.22.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 0.23.17, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.0.0-M38, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

x_refsource_CONFIRMExploitMitigationThird Party Advisory
Source: [email protected]
https://github.com/http4s/http4s/security/advisories/GHSA-54w6-vxfh-fw7f

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-20

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