CVE-2026-34085 Memory corruption in fontconfig
An off-by-one error in fontconfig allows attackers to trigger a one-byte out-of-bounds write, potentially leading to code execution or crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34085?
CVE-2026-34085 is a medium-severity memory corruption vulnerability in fontconfig, published on 25 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
fontconfig before 2.17.1 has an off-by-one error in allocation during sfnt capability handling, leading to a one-byte out-of-bounds write, and potentially a crash or code execution. This is in FcFontCapabilities in fcfreetype.c.
Weakness: CWE-193
Which versions are affected by CVE-2026-34085?
It affects 1 product.
Linux distribution packages (3)
fontconfig Red Hat:hummingbird:1 | All versions | 0:2.17.1-0.1.hum1 |
fontconfig-devel Red Hat:hummingbird:1 | All versions | 0:2.17.1-0.1.hum1 |
fontconfig-devel-doc Red Hat:hummingbird:1 | All versions | 0:2.17.1-0.1.hum1 |
Products include Fontconfig Project Fontconfig.
How do I fix CVE-2026-34085?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-34085 being exploited?
There is no known exploitation of CVE-2026-34085 in the wild and no public exploit code.
Sources
Also known as GHSA-jxv8-p782-98cx, JLSEC-2026-79, RHSA-2026:13722.