CVE-2026-5545
Description
A flaw was found in libcurl. An application using libcurl that performs an authenticated HTTP(S) request after a Negotiate-authenticated one to the same host may incorrectly reuse the previous connection. This authentication bypass vulnerability allows the second request to be sent over a connection authenticated with different credentials, potentially leading to unauthorized access or information disclosure.
Statement
Moderate: A flaw in libcurl allows for the wrong reuse of HTTP Negotiate authenticated connections. This can occur when an application makes an authenticated HTTP(S) request after a Negotiate-authenticated one to the same host, potentially leading to a request being sent over a connection authenticated with unintended credentials. This issue affects applications using libcurl versions from 7.10.6 up to and including 8.19.0.
Mitigation
To mitigate this issue, applications using libcurl can disable connection reuse. This can be achieved by setting one of the following libcurl options: CURLOPT_FRESH_CONNECT to force a new connection for each request, CURLOPT_MAXCONNECTS to limit the total number of open connections, or CURLMOPT_MAX_HOST_CONNECTIONS when using the curl_multi API to limit connections per host. Disabling connection reuse may impact application performance due to increased overhead for establishing new connections.
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 | 6.5 | 6.5 | 6.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | High | High |
| Privileges Required | Low | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | Low | Low |
| Integrity Impact | High | High | High |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Frequently Asked Questions
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