FreeType Out-of-Bounds Write (CVE-2025-27363)

Historical catalog analysis: CISA added this entry on May 06, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2025-27363 is an out-of-bounds write vulnerability (CWE-787) identified in FreeType. The flaw occurs during the parsing of font subglyph structures specifically associated with variable font files and TrueType GX. If triggered, this memory corruption could allow for arbitrary code execution.

Exposure and applicability

FreeType is a widely deployed open-source library used across numerous operating systems, applications, and embedded devices to render fonts. Because it is integrated as a third-party component into various proprietary products, exposure is not limited to a single application but extends to any software that utilizes FreeType for font processing.

Infrastructure owners should identify assets that process external or untrusted font files, as the vulnerability is triggered during the parsing phase of specific TrueType GX and variable font structures.

Remediation priorities

Given its inclusion in CISA’s Known Exploited Vulnerabilities (KEV) catalog on May 6, 2025, this vulnerability should be prioritized for immediate remediation. Our analysis suggests the following priority sequence:

1. Vendor Inventory: Identify all third-party software and OS distributions that incorporate FreeType. Because this is a library vulnerability, patching requires updates from the specific product vendor rather than a direct update to the library in most managed environments.
2. Patch Deployment: Apply security updates provided by vendors according to their specific instructions. For cloud services, organizations should align with BOD 22-01 guidance where applicable.
3. Component Decommissioning: In scenarios where a vendor has not provided a mitigation or patch for an affected system, the source suggests discontinuing use of the product to eliminate the exposure path.

How to validate remediation

Verification must move beyond simple version checks, as library versions can be renamed or bundled differently by various vendors. To verify that exposure has been reduced, defenders should:

• Cross-Reference Vendor Advisories: Match the installed software version against the specific patched version listed in the vendor’s security bulletin for CVE-2025-27363.
• Binary Analysis: In high-assurance environments, verify that the linked FreeType library within the application has been updated to a version containing the fix for the out-of-bounds write in the GX/variable font parsing logic.

Limits and open questions

There is currently no information regarding whether this vulnerability is being utilized by known ransomware campaigns. Additionally, because FreeType is embedded across diverse platforms, there is no single universal patch; remediation is dependent on the responsiveness of individual upstream vendors. Residual risk remains for any legacy systems that are no longer supported by vendors but continue to process font files.

Source and editorial note

CVE-2025-27363: FreeType Out-of-Bounds Write Vulnerability · Source date: May 06, 2025 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: May 09, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: October 16, 2026 at 00:06 UTC.

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