Is CVE-2026-12549 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-12549 being exploited in the wild.

How severe is CVE-2026-12549?

Medium severity, with a CVSS score of 4.8, published 22 June 2026.

Is there a fix for CVE-2026-12549?

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-2026-12549 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-12549?

Check whether you run Gnome Libsoup, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 or one of the others listed 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.

CVE-2026-12549: GNOME libsoup buffer access error in Range header parsing

CVE-2026-12549 · Severity: medium · CVSS 4.8 · Published 2026-06-22

libsoup is a widely used HTTP client/server library for GNOME and Linux systems. A flaw in how it handles specific web requests (Range requests) allows an unauthenticated attacker to trigger malformed responses and flood system logs with error messages. In some development or debug environments, this could also cause the application to crash, potentially leading to a service outage.

Technologies: Gnome Libsoup, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9. Vendors: Gnome, Red Hat.

Quick answers

Is CVE-2026-12549 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-12549 being exploited in the wild.
How severe is CVE-2026-12549?: Medium severity, with a CVSS score of 4.8, published 22 June 2026.
Which products and versions are affected?: Gnome Libsoup 3.4.x, 3.6.x.
Is there a fix for CVE-2026-12549?: 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-2026-12549 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-12549?: Check whether you run Gnome Libsoup, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 or one of the others listed 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 regression in libsoup (specifically in soup-message-headers.c) occurred when a rework commit replaced specific overflow checks with a general signed comparison. When a client sends an HTTP Range request with a suffix length (e.g., 'bytes=-N') exceeding the total content length, the library calculates a negative start offset. Because of a signed comparison error (treating the negative start as larger than the end), the value is not clamped to zero. This results in malformed Content-Range headers, GLib-CRITICAL log flooding, and potential SIGABRT crashes in debug builds when the negative value is passed to memory functions. The vulnerability affects both libsoup 2.x and 3.x branches.

Affected products

Red Hat libsoup3 3.4.x, 3.6.x
GNOME libsoup master, 3.4.x, 3.6.x
Red Hat Red Hat Enterprise Linux 8
Red Hat Red Hat Enterprise Linux 9
Red Hat Red Hat Enterprise Linux 10

Timeline

2026-06-17: disclosed: Issue reported to GNOME/Red Hat Bugzilla
2026-06-22: advisory: NVD and Red Hat published advisory details

References

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