Description
A flaw was found in libsoup. After a CONNECT tunnel is established through an HTTP proxy, libsoup incorrectly attaches the Proxy-Authorization header to subsequent HTTPS requests sent through that tunnel to the destination server. This allows the destination server to capture proxy credentials, leading to information disclosure.
Published: 2026-07-24
Score: 6.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

Libsoup allows a Proxy-Authorization header that contains proxy credentials to be mistakenly attached to HTTPS requests after a CONNECT tunnel is established. The flaw results in proxy credentials being forwarded to the destination server, giving the server unintended visibility into authentication information. This vulnerability is classified as CWE-201 and directly leads to sensitive data exposure.

Affected Systems

The issue affects Red Hat Enterprise Linux releases 10, 6, 7, 8, and 9 through the embedded libsoup component. Version details are not specified, implying all current releases of these operating systems are impacted.

Risk and Exploitability

The CVSS score is 6.5, indicating a moderate severity. The EPSS score of less than 1% suggests a low probability of exploitation at the time of analysis, and the vulnerability is not listed in the CISA KEV catalog. Based on the description, the likely attack vector requires an attacker who can control or influence the HTTP proxy used by a client; such an attacker could submit a CONNECT request that triggers the header leakage, allowing the destination server to capture the credentials.

Generated by OpenCVE AI on August 3, 2026 at 19:39 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Check the Red Hat Customer Portal for the latest security update that addresses the libsoup credential leakage and apply the patch to all affected RHEL systems.
  • Configure the network to restrict CONNECT proxy usage so that only trusted proxies can establish tunnels, reducing the exposure of proxy authentication headers.
  • Verify that the proxy does not forward Proxy‑Authorization headers to downstream servers and enforce that TLS connections are established directly from the client to the destination server whenever possible.

Generated by OpenCVE AI on August 3, 2026 at 19:39 UTC.

Tracking

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Advisories

No advisories yet.

History

Mon, 27 Jul 2026 15:45:00 +0000

Type Values Removed Values Added
First Time appeared Libsoup
Libsoup libsoup
Vendors & Products Libsoup
Libsoup libsoup

Fri, 24 Jul 2026 23:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in libsoup. After a CONNECT tunnel is established through an HTTP proxy, libsoup incorrectly attaches the Proxy-Authorization header to subsequent HTTPS requests sent through that tunnel to the destination server. This allows the destination server to capture proxy credentials, leading to information disclosure.
Title Libsoup: libsoup: proxy credentials leak to destination server via proxy-authorization header in connect tunnels
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-201
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N'}

Subscriptions

Libsoup Libsoup
Redhat Enterprise Linux
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-07-28T14:55:26.084Z

Reserved: 2026-07-24T22:32:18.748Z

Link: CVE-2026-66339

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-07-24T23:16:52.187

Modified: 2026-07-28T16:20:11.980

Link: CVE-2026-66339

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-03T19:45:07Z

Weaknesses
  • CWE-201

    Insertion of Sensitive Information Into Sent Data