CVE-2026-107231

Received Received - Intake

Realm.Builder Digest Challenge Authentication Bypass in AsyncHttpClient

Publication date: 2026-10-07

Last updated on: 2026-10-07

Assigner: GitHub, Inc.

Description

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.13 and 2.16.1, Realm.Builder treats a Digest challenge that yields no usable nonce as a Basic challenge. A malicious origin or proxy can label a challenge Digest while omitting or emptying the nonce, causing the client to resend the username and password using reversible Basic authentication. Both origin and proxy challenge parsers are affected. This issue is fixed in versions 3.0.13 and 2.16.1.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-07

Last Modified

2026-10-07

Generated

2026-10-08

AI Q&A

2026-10-08

EPSS Evaluated

N/A

NVD

CVE-2026-107231

Affected Vendors & Products

Vendor	Product	Version / Range
AsyncHttpClient	async-http-client	>= 3.0.0.Beta1, < 3.0.13
AsyncHttpClient	async-http-client	>= 2.0.0, < 2.16.1

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-522	The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.
CWE-757	A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties.
CWE-319	The product transmits sensitive or security-critical data in cleartext in a communication channel that can be sniffed by unauthorized actors.

Attack-Flow Graph

Executive Summary

The AsyncHttpClient (AHC) library is used by Java applications to execute HTTP requests and process responses. A vulnerability exists in versions prior to 3.0.13 and 2.16.1 where the library incorrectly handles Digest authentication challenges. If a Digest challenge lacks a usable nonce, the library treats it as a Basic challenge, forcing the client to resend credentials in plaintext using Basic authentication.

Detection Guidance

To detect this vulnerability, check if your system uses AsyncHttpClient versions prior to 3.0.13 or 2.16.1. Inspect dependency files like pom.xml or build.gradle for the library version. Monitor network traffic for Basic authentication headers sent in response to Digest challenges without a nonce.

Impact Analysis

An attacker could exploit this to intercept and capture credentials sent in plaintext during HTTP requests. This could lead to unauthorized access to sensitive systems or data if the credentials are reused elsewhere. The impact is higher in environments where Basic authentication is used over unencrypted channels.

Compliance Impact

This vulnerability could violate compliance requirements that mandate encryption of credentials, such as GDPR (data protection) and HIPAA (healthcare data). Exposure of plaintext credentials may result in data breaches, leading to legal penalties, reputational damage, and loss of trust.

Mitigation Strategies

Update the AsyncHttpClient library to version 3.0.13 or later, or 2.16.1 or later, to address the issue where Digest challenges without a usable nonce are incorrectly treated as Basic challenges.

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