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Http4s improperly parses User-Agent and Server headers

High severity GitHub Reviewed Published Jan 4, 2023 in http4s/http4s • Updated Jan 30, 2023

Package

maven org.http4s:http4s-core (Maven)

Affected versions

>= 0.1.0, < 0.21.34
>= 0.22.0, < 0.22.15
>= 0.23.0, < 0.23.17
>= 1.0.0-M1, < 1.0.0-M38

Patched versions

0.21.34
0.22.15
0.23.17
1.0.0-M38

Description

Impact

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.

v0.21.x

val unsafe: Option[`User-Agent`] = req.headers.get(`User-Agent`)

v0.22.x, v0.23.x, v1.x

val unsafe: Option[`User-Agent`] = req.headers.get[`User-Agent`]
val alsoUnsafe: Option[`Server`] = req.headers.get[Server]

Patches

Fixes are released in 0.21.34, 0.22.15, 0.23.17, and 1.0.0-M38.

Workarounds

Use the weakly typed header interface

v0.21.x
val safe: Option[Header] = req.headers.get("User-Agent".ci)
// but don't do this
val unsafe = header.map(_.parsed)
v0.22.x, v0.23.x, v1.x
val safe: Option[Header] = req.headers.get(ci"User-Agent")

References

@rossabaker rossabaker published to http4s/http4s Jan 4, 2023
Published by the National Vulnerability Database Jan 4, 2023
Published to the GitHub Advisory Database Jan 6, 2023
Reviewed Jan 6, 2023
Last updated Jan 30, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

0.077%
(34th percentile)

Weaknesses

CVE ID

CVE-2023-22465

GHSA ID

GHSA-54w6-vxfh-fw7f

Source code

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