CVE-2026-107283: AsyncHttpClient: Digest authentication cnonce generated with a non-cryptographic random source
Impact The client nonce used in HTTP Digest authentication was generated from ThreadLocalRandom, a fast but non-cryptographic pseudorandom number generator. RFC 7616 section 3.3 requires the cnonce to be unpredictable, since it is part of what protects the Digest exchange against chosen-plaintext and precomputation attacks on the credentials. An attacker able to observe or influence enough of the generator's output could reduce the unpredictability the protocol depends on. NTLM (and, on the 3.x line, SCRAM) in this client already use SecureRandom for their own nonces; Digest did not.
Affected versions 3.x: up to and including 3.0.11 2.x: up to and including 2.16.0
Patches Fixed in 3.0.12 on the 3.x line and in 2.16.1 on the 2.x line. The cnonce is now generated with SecureRandom, matching the other authentication schemes in the client.
Workarounds None available from application code.
Details Realm.Builder's cnonce generation seeded its bytes from ThreadLocalRandom.current() rather than a SecureRandom instance.
Other sources
The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.12 and 2.16.1, Realm.Builder generates the HTTP Digest client nonce with ThreadLocalRandom rather than a cryptographically secure random source. Digest relies on an unpredictable cnonce to resist chosen-plaintext and credential precomputation attacks, so an observer able to infer generator state can reduce the protection of the authentication exchange. This issue is fixed in versions 3.0.12 and 2.16.1.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
maven/org.asynchttpclient:async-http-clientto a version that resolves this vulnerability.Fixed in 2.16.1 - Upgrade
Upgrade
maven/org.asynchttpclient:async-http-clientto a version that resolves this vulnerability.Fixed in 3.0.12 - Upgrade
Upgrade
AsyncHttpClientto a version that resolves this vulnerability.Fixed in 3.0.12 - Upgrade
Upgrade
AsyncHttpClientto a version that resolves this vulnerability.Fixed in 2.16.1
Event History
Frequently Asked Questions
Which deployments are exposed?
Java applications using AsyncHttpClient versions earlier than 3.0.12 or 2.16.1 are affected when they use HTTP Digest authentication through Realm.Builder. The issue concerns the client nonce generated for Digest authentication exchanges.
What does an attacker need to exploit this weakness?
An attacker needs to observe the Digest authentication exchange and be able to infer the state of the ThreadLocalRandom generator used to create the client nonce. This can reduce Digest authentication's resistance to chosen-plaintext and credential precomputation attacks.
What is the remediation?
Upgrade AsyncHttpClient to version 3.0.12 or 2.16.1, which replace the non-cryptographic random source used for the Digest client nonce.