What is CVE-2018-12911?

CVE-2018-12911 is a critical-severity vulnerability in Webkitgtk Webkitgtk\+, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2018-07-19.

How severe is CVE-2018-12911?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Webkitgtk Webkitgtk\+

CVE-2018-12911

WebKitGTK+ 2.20.3 has an off-by-one error, with a resultant out-of-bounds write, in the get_simple_globs functions in ThirdParty/xdgmime/src/xdgmimecache.c and ThirdParty/xdgmime/src/xdgmimeglob.c.

Vulnerability class: Buffer Overflow

Published 2018-07-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.017 (76.7th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 77th percentile — 76.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000

Affected products

Webkitgtk Webkitgtk\+ — versions 2.20.3
Canonical Ubuntu Linux — versions 16.04, 18.04

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

usn.ubuntu.com/3743-1/ (vendor-advisory, Third Party Advisory)
trac.webkit.org/changeset/233404/webkit (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2018-12911?: CVE-2018-12911 is a critical-severity vulnerability in Webkitgtk Webkitgtk\+, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2018-07-19.
How severe is CVE-2018-12911?: Critical severity. CVSS v3 base score is 9.8 out of 10.