CVE-2026-6253
Description
A flaw was found in curl. When curl is configured to use distinct proxies for different URL schemes, a redirect from a URL using an authenticated proxy to one using an unauthenticated proxy can inadvertently expose the initial proxy's credentials. This improper credential management (CWE-522) may allow an attacker to gain unauthorized access or information by intercepting these disclosed credentials.
Statement
Moderate: This flaw in curl and libcurl allows proxy credentials to be inadvertently exposed to a second proxy during a redirect. This issue arises when curl is configured to use distinct proxies for different URL schemes, the initial proxy requires authentication, and a subsequent proxy does not. Red Hat products utilizing curl or libcurl in such a specific proxy chaining configuration may be affected.
Mitigation
To mitigate this issue, avoid configuring curl or libcurl to use proxies that require credentials. This prevents the scenario where credentials for a first proxy could be inadvertently passed to a second proxy during a redirect.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 5.9 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
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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