# CVE-2026-12547: GNOME libsoup information disclosure in SoupAuthManager proxy credential handling

Source: https://junglewise.ai/threats/cve-2026-12547-gnome-libsoup-information-disclosure-in-soupauthmanager-proxy  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-21. Updated: 2026-07-21  
License: CC BY 4.0 with a link back

CVE-2026-12547 · Severity: low · CVSS 3.4 · Published 2026-07-21

libsoup is a networking library used by many Linux applications to handle web requests. A flaw in how it manages proxy server authentication allows sensitive login credentials intended for one proxy server to be accidentally sent to a different proxy server if the system's network configuration changes. This could allow an attacker who controls a secondary proxy server to capture enterprise credentials when a user switches networks or updates their settings.

Technologies: [Gnome Libsoup](https://junglewise.ai/threats/technologies/libsoup). Vendors: [Gnome](https://junglewise.ai/threats/vendors/gnome).

## Quick answers

**Is CVE-2026-12547 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12547 being exploited in the wild.

**How severe is CVE-2026-12547?** Low severity, with a CVSS score of 3.4, published 21 July 2026.

**Which products and versions are affected?** Gnome Libsoup Red Hat Enterprise Linux 10.

**Is there a fix for CVE-2026-12547?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-12547 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-12547?** Check whether you run Gnome Libsoup at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in libsoup's SoupAuthManager where proxy authentication state is cached globally rather than being scoped to a specific proxy authority (host:port). When a session's proxy configuration is updated (e.g., via system settings or WPAD) after an initial authentication has occurred, the library incorrectly attaches the cached 'Proxy-Authorization' header from the previous proxy to requests sent to the new proxy. An attacker who can influence proxy settings or provide a malicious proxy can capture these leaked credentials. The issue is tracked in libsoup's internal work items and affects versions used in Red Hat Enterprise Linux 10 and other GNOME-based environments.

## Affected products

- Red Hat libsoup3 Red Hat Enterprise Linux 10
- GNOME libsoup

## Timeline

- 2026-01-25: disclosed: Vulnerability reported via YesWeHack
- 2026-06-17: other: Bug report opened in Red Hat Bugzilla
- 2026-07-21: advisory: CVE published to NVD

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-12547](https://access.redhat.com/security/cve/CVE-2026-12547)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2489994](https://bugzilla.redhat.com/show_bug.cgi?id=2489994)
- [https://gitlab.gnome.org/GNOME/libsoup/-/work_items/506](https://gitlab.gnome.org/GNOME/libsoup/-/work_items/506)

## Related threats

- [libsoup HTTP request smuggling via undrained Expect: 100-continue body](https://junglewise.ai/threats/cve-2026-103399-a-flaw-was-found-in-soupserver-libsoup-when-an-http-1-x-client)
- [libsoup heap buffer overflow in permessage-deflate WebSocket extension](https://junglewise.ai/threats/cve-2026-102560-a-flaw-was-found-in-libsoup-when-the-permessage-deflate)
- [libsoup heap buffer overflow in WebSocket handling](https://junglewise.ai/threats/cve-2026-102558-a-flaw-was-found-in-libsoup-when-max-incoming-payload-size-is)
- [libsoup out-of-bounds read in data-URI base64 decoding](https://junglewise.ai/threats/cve-2026-102555-a-flaw-was-found-in-libsoup-the-soup-uri-decode-data-uri)
- [libsoup heap corruption in WebSocket message reassembly](https://junglewise.ai/threats/cve-2026-102557-a-flaw-was-found-in-libsoup-when-reassembling-fragmented)