Vulnerability in GNOME Libsoup
CVE-2026-12549
The fix for CVE-2026-2443 was regressed by a subsequent rework commit that replaced specific overflow checks with a general signed comparison. When a client sends a Range request with a suffix length exceeding the content size, the resulting negative start value is not properly clamped, leading to malformed HTTP 206 responses and log flooding.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L.
EPSS exploit prediction
EPSS: 0.004 (32.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 32.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-12549 (Mitigation, vdb-entry, Vendor Advisory)
- access.redhat.com/security/cve/cve-2026-0716 (technical-description, Mitigation, Vendor Advisory)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Issue Tracking, Vendor Advisory)
- gitlab.gnome.org/GNOME/libsoup/-/work_items/516 (Exploit, Patch, Issue Tracking, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-12549?
- CVE-2026-12549 is a medium-severity vulnerability in GNOME Libsoup, classified under Buffer Access with Incorrect Length Value. CVSS score: 4.8/10. Published 2026-06-22.
- How severe is CVE-2026-12549?
- Medium severity. CVSS v3 base score is 4.8 out of 10.