Quick answers
- Is CVE-2026-12548 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-12548 being exploited in the wild.
- How severe is CVE-2026-12548?
- Medium severity, with a CVSS score of 4.2, published 21 July 2026.
- Which products and versions are affected?
- Gnome Libsoup Red Hat Enterprise Linux 10 (affected).
- Is there a fix for CVE-2026-12548?
- 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-2026-12548 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-12548?
- 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 heap out-of-bounds read (CWE-125) exists in libsoup's multipart body parser due to an integer truncation vulnerability. In `soup_multipart_new_from_message()`, the length of a MIME part's header section is calculated as a 64-bit `ptrdiff_t`. When this value exceeds `INT_MAX` (approx. 2 GiB), it is truncated to a 32-bit signed `int` when passed to `soup_headers_parse()`, resulting in a negative value. This negative integer is subsequently cast to a large `size_t` when passed to `memchr()`, triggering a massive out-of-bounds read. An attacker can exploit this by sending a crafted multipart HTTP message to a libsoup-based client or server to cause a denial of service (crash) or potentially disclose heap memory contents.
Affected products
- Red Hat libsoup3 Red Hat Enterprise Linux 10 (affected)
- GNOME libsoup 3.x versions prior to fix
Timeline
- 2026-01-28: disclosed: Reported via YesWeHack program
- 2026-07-21: advisory: NVD and Red Hat published advisory details