CVE-2026-86415
Description
A flaw was found in curl. In builds configured with the Microsoft Schannel Transport Layer Security (TLS) backend, libcurl's connection cache fails to evaluate client certificate authentication settings when handling HTTP redirects. A malicious server can redirect a transfer to a different destination, causing curl to inappropriately reuse an already authenticated connection. This issue can result in information disclosure by exposing client certificates and credentials to unintended origins.
Statement
This vulnerability is rated as Low impact for Red Hat products because exploitation is restricted to builds utilizing the Windows-specific Schannel TLS backend. Red Hat distributions compile curl and libcurl with OpenSSL rather than Schannel. As a result, the vulnerable code paths are not present or active in Red Hat environments.
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 | 3.7 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | None |
| Integrity Impact | None | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.
Acknowledgements
Red Hat would like to thank Stanislav Fort (Aisle Research) for reporting this issue.
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