Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-07-03T06:16:06 libcurl: libcurl: Information disclosure due to uncleared proxy authentication state 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N CWE-201

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against `proxyA` using Digest auth, a subsequent transfer routed through `proxyB` erroneously leaks the `Proxy-Authorization:` header intended solely for `proxyA`.

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.

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 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. Red Hat Hardened Images 2026-06-24T00:00:00Z RHSA-2026:29017 curl-main-8.21.0-0.1.hum1 Red Hat Hardened Images 2026-07-02T00:00:00Z RHSA-2026:34975 rust-main-1.96.1-1.hum1 Red Hat Enterprise Linux 8 Not affected dotnet8.0 Red Hat JBoss Core Services Affected libcurl-1.dll Red Hat JBoss Core Services Affected libcurl.so https://www.cve.org/CVERecord?id=CVE-2026-8927 https://nvd.nist.gov/vuln/detail/CVE-2026-8927 https://curl.se/docs/CVE-2026-8927.html https://curl.se/docs/CVE-2026-8927.json https://hackerone.com/reports/3744543