CVE-2026-77711
Description
A flaw was found in Eclipse Jetty's HttpClient. A malicious destination server can cause an information disclosure of proxy authentication credentials when client requests are routed through a forward proxy. By returning a proxy authentication challenge, the server misleads the client into believing the response came from the proxy, causing the client to re-send the request containing sensitive credentials directly to the untrusted server.
Statement
This flaw is rated Important because an HTTPS origin reachable through an authenticating forward proxy can forge a 407 response and trick Eclipse Jetty's HttpClient into sending the proxy's Basic credentials through the established TLS tunnel directly to that origin. Exploitation only requires a client configured with forward-proxy authentication connecting to an attacker-controlled or compromised HTTPS destination; the leaked credentials could then be reused against the proxy.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Files or Directories; Read Memory; Read Application Data
Sensitive data may be exposed to attackers.
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