Meta has issued a warning regarding a critical security flaw in the FreeType open-source font rendering library, highlighting potential active exploitation. The vulnerability, designated as CVE-2025-27363, has been assigned a CVSS severity score of 8.1, classifying it as a high-risk threat.
Understanding CVE-2025-27363
The vulnerability stems from an out-of-bounds write flaw present in FreeType versions 2.13.0 and earlier. When processing certain font files, the bug can be exploited to enable remote code execution (RCE), making it a severe security risk.
According to Meta’s advisory:
“An out-of-bounds write exists in FreeType versions 2.13.0 and below when attempting to parse font subglyph structures related to TrueType GX and variable font files.”
The root cause of the flaw lies in improper handling of memory allocations. Specifically, the vulnerable code assigns a signed short value to an unsigned long, then applies a static value that wraps around and allocates an undersized heap buffer. This causes the system to write up to six signed long integers out of bounds, potentially leading to arbitrary code execution.
Active Exploitation and Risk Factors
While Meta has not disclosed specific details about how the flaw is being exploited, who the attackers are, or the scale of the attacks, the company has confirmed that real-world exploitation is likely occurring.
Security researchers emphasize that if left unpatched, attackers could leverage this flaw to gain unauthorized access, execute malicious code, and compromise entire systems.
Affected Systems and Linux Distributions
Further analysis reveals that multiple Linux distributions are still running outdated FreeType versions, leaving them exposed to potential attacks. The affected distributions include:
AlmaLinux
Alpine Linux
Amazon Linux 2
Debian Stable / Devuan
RHEL / CentOS Stream / AlmaLinux 8 and 9
GNU Guix
Mageia
OpenMandriva
openSUSE Leap
Slackware
Ubuntu 22.04
Security experts warn that any system running these distributions with outdated FreeType libraries remains vulnerable to potential exploitation.
FreeType Developers Respond
Werner Lemberg, a FreeType developer, confirmed to The Hacker News that the vulnerability had been addressed nearly two years ago. He reassured users that FreeType versions newer than 2.13.0 are no longer affected.
However, many Linux distributions have yet to update their FreeType package, increasing the risk of real-world attacks.
How to Protect Your System
Given the active exploitation and severity of the flaw, users and administrators are strongly urged to take immediate action:
Update FreeType to version 2.13.3 (the latest patched version).
Check for package updates in your respective Linux distribution.
Monitor security advisories from your OS vendor for any additional patches or mitigations.
Implement security best practices, such as restricting font parsing to trusted sources and enforcing strict access controls.
Final Thoughts
The FreeType vulnerability CVE-2025-27363 underscores the importance of timely software updates and proactive cybersecurity measures. With active exploitation in progress, unpatched systems remain at risk of potential attacks leading to remote code execution and full system compromise.
Administrators and users should not delay applying the latest patches to safeguard their systems. Keeping security libraries like FreeType updated is crucial in mitigating emerging threats and ensuring long-term cybersecurity resilience.
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