The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. A vulnerability has been identified in versions of AsyncHttpClient prior to 3.0.9 and 2.14.5, specifically when the redirect following feature is enabled. This vulnerability allows for the forwarding of Authorization and Proxy-Authorization headers, along with Realm credentials, to arbitrary redirect targets regardless of domain, scheme, or port changes. As a result, sensitive credentials may be leaked on cross-domain redirects and HTTPS-to-HTTP downgrades.
The risk to organizations includes potential exposure of Bearer tokens, Basic auth credentials, and any other Authorization header value to attackers who control a redirect target. Such control can be achieved through methods like open redirects, DNS rebinding, or man-in-the-middle (MITM) attacks on HTTP. The fix introduced in versions 3.0.9 and 2.14.5 automatically strips these sensitive headers whenever a redirect crosses origin boundaries or downgrades from HTTPS to HTTP.
For users unable to upgrade to the fixed versions, it is crucial to set the configuration option `(stripAuthorizationOnRedirect(true))`. However, due to inherent limitations in versions prior to 3.0.9 and 2.14.5, this setting alone may not be sufficient, as the Realm object containing plaintext credentials may still be propagated. Alternatively, users should consider disabling redirect following by setting `followRedirect(false)` and manually handling redirects with proper origin validation.
Organizations should prioritize patching immediately, as the exploitation of this vulnerability can lead to significant credential theft and unauthorized access to sensitive data.
Vulnerability Details
The vulnerability is classified as a medium severity issue with a CVSS score of 6.8. The CVSS vector string for this vulnerability is CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N, indicating that it is exploitable over the network with a high attack complexity and no privileges or user interaction required. The confidentiality impact is rated as high, while integrity and availability impacts are none.
Technical Analysis
The root cause of this vulnerability lies in the handling of HTTP redirects within the AsyncHttpClient library. When redirect following is enabled, sensitive headers are forwarded to potentially malicious redirect targets. The attack vector is categorized as NETWORK, meaning it can be exploited remotely. The attack complexity is high due to the requirement for an attacker to control the redirect target.
No privileges are required for an attacker to exploit this vulnerability, and user interaction is not necessary. The impact on confidentiality is significant, as it allows the potential capture of sensitive authentication tokens and credentials.
Risk & Impact Analysis
Real-world deployment risks include the potential for attackers to leverage this vulnerability to capture sensitive authentication information during legitimate user interactions. Organizations using the affected versions of AsyncHttpClient should be particularly cautious about handling redirects and validating the origins of redirection requests.
The blast radius of this vulnerability could extend to any organization utilizing the AsyncHttpClient library for HTTP requests. Additionally, the fact that the vulnerability affects various versions increases the urgency for organizations to address it within their priority patch cycles.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
This vulnerability affects all versions of AsyncHttpClient prior to 3.0.9 and 2.14.5. Organizations using these versions should take immediate action to upgrade to the fixed versions to mitigate potential risks.
Mitigation & Remediation
To mitigate this vulnerability, organizations should upgrade to AsyncHttpClient version 3.0.9 or 2.14.5. For those unable to upgrade immediately, it is advised to configure the client to strip authorization headers by setting `(stripAuthorizationOnRedirect(true))`. However, this setting alone may not suffice due to inherent limitations in earlier versions.
Additionally, organizations should consider disabling redirect following by using `followRedirect(false)` and implement manual handling of redirects with proper origin validation. These measures can help to prevent credential leakage effectively.
For further insights on securing application environments, organizations may benefit from consulting resources on application security assessments that identify and rectify vulnerabilities in their systems.
Detection Guidance
Organizations should monitor for any unusual HTTP traffic patterns that may indicate attempts to exploit this vulnerability, particularly focusing on redirects that involve sensitive authorization headers. Key indicators to watch include unexpected redirects to untrusted domains and repeated access attempts to sensitive endpoints.
AppSecure Threat Intelligence Insight
Understanding the long-term implications of this vulnerability is critical for organizations that rely on the AsyncHttpClient library. It represents a pattern where improper handling of redirects can lead to significant credential exposure. Security teams should conduct thorough reviews of their redirect handling practices and ensure that proper validation mechanisms are in place.
For more information on securing API endpoints, organizations may refer to the best practices for API security. Additionally, insights on the importance of continuous security testing can be found in the continuous security testing guide. Finally, organizations should consider a comprehensive approach to their vulnerability management by reviewing the vulnerability management program design.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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