Out-of-bounds Read in Red Hat Enterprise Linux 10
CVE-2026-12478
The fix for CVE-2026-0716 (commit 6ff7ef0, libsoup 3.6.6) placed the integer overflow guard inside the if (masked) block, leaving unmasked server-to-client frames unprotected. A malicious WebSocket server can send a crafted unmasked frame with a payload length near UINT64_MAX to trigger an OOB read in a libsoup-based client when max_incoming_payload_size is set to 0.
Vulnerability class: Buffer Overflow
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: 0.002 (14.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 14.4% 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: 0.002 · change: -0.001
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- access.redhat.com/security/cve/CVE-2026-12478 (vdb-entry)
- access.redhat.com/security/cve/cve-2026-0716 (technical-description)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking)
- gitlab.gnome.org/GNOME/libsoup/-/merge_requests/518
Frequently asked questions
- What is CVE-2026-12478?
- CVE-2026-12478 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, classified under Out-of-bounds Read. CVSS score: 4.8/10. Published 2026-07-14.
- How severe is CVE-2026-12478?
- Medium severity. CVSS v3 base score is 4.8 out of 10.
- Is CVE-2026-12478 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.