CVE-2026-8927
Description
A flaw was found in libcurl. When reusing a libcurl handle for sequential transfers with environment-variable proxy configuration, the library does not properly clear the proxy authentication state. This oversight can lead to the unintended disclosure of Proxy-Authorization headers to an incorrect proxy, potentially exposing sensitive authentication information to an unauthorized entity. This is an information disclosure vulnerability.
Statement
This Important information disclosure vulnerability in libcurl arises when a handle is reused for sequential transfers with environment-variable proxy configurations, failing to clear the proxy authentication state. This oversight can lead to Proxy-Authorization headers being inadvertently sent to an incorrect proxy, potentially exposing sensitive authentication information in Red Hat environments utilizing multiple proxy configurations. This flaw leads only to a confidentiality impact. There has been no observed integrity impact.
Mitigation
To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
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 | 7.5 | N/A | 9.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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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