Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, DigestAuth replay protection records lastNc plus one instead of the highest nonce-count value it has accepted. When a legitimate client sends noncontiguous nc values because of parallel or retried requests, the stored counter remains below the accepted maximum, allowing a passive observer to replay a captured Authorization header multiple times.
Successful replays execute authenticated requests, including state-changing operations, as the captured user. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://github.com/http4s/http4s/commit/7f065101c45f3d86bc105e8fc6323c2c4a11471f
security-advisories@github.com
https://github.com/http4s/http4s/releases/tag/v0.23.35
security-advisories@github.com
https://github.com/http4s/http4s/releases/tag/v1.0.0-M47
security-advisories@github.com
https://github.com/http4s/http4s/security/advisories/GHSA-9xww-74xv-gjfp
security-advisories@github.com