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 vulnerable code assigns a signed short value to an unsigned long and then adds a static value causing it to wrap around and allocate too small of a heap buffer. The code then writes up to 6 signed long integers out of bounds relative to this buffer. This may result in arbitrary code execution. This vulnerability may have been exploited in the wild.
With a CVSS score of 8.1, this high-severity vulnerability poses a significant risk to organizations utilizing Debian systems. Given the potential for arbitrary code execution, it is crucial for defenders to assess their systems and implement necessary mitigations promptly.
The vulnerability has been confirmed to have known exploit availability, increasing the urgency for organizations to patch their systems. Organizations should prioritize patching immediately to mitigate any associated risks.
The FreeType project has provided updated versions that resolve this vulnerability, and it is highly recommended that organizations upgrade to these versions to ensure their systems are secure.
In addition to patching, organizations should consider implementing additional security measures such as monitoring and network controls to prevent potential exploitation of this vulnerability.
Vulnerability Details
CVE-2025-27363 is characterized by an out of bounds write vulnerability in FreeType. The vulnerability allows attackers to exploit the system by manipulating the font subglyph structures related to TrueType GX and variable font files. The CVSS score of 8.1 indicates a high severity level, necessitating prompt action from organizations to mitigate the associated risks.
Technical Analysis
The root cause of this vulnerability lies in the handling of data types. The vulnerable code assigns a signed short value to an unsigned long, which can lead to a wrap-around and result in a heap buffer that is too small. As a consequence, writing up to 6 signed long integers out of bounds can occur, leading to potential arbitrary code execution.
The attack vector for this vulnerability is network-based, with a high attack complexity. This means that although exploitation is possible, it may require a certain level of skill and knowledge to execute successfully.
Risk & Impact Analysis
Risk to organizations includes the potential for unauthorized access and arbitrary code execution. Given the nature of the vulnerability, if exploited, it could lead to significant data breaches or system compromises.
Organizations should address this vulnerability in their priority patch cycle. The potential blast radius is considerable, affecting not only the vulnerable FreeType component but any application dependent on it.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | Yes |
Ransomware Use | No |
Affected Versions
All versions of FreeType prior to 2.13.0 are affected by this vulnerability. Organizations using Debian Linux 11.0 may also be impacted and should verify their systems' configurations.
Mitigation & Remediation
Organizations should patch their systems to the latest version of FreeType that resolves this vulnerability. For Debian users, the recommended action is to upgrade to the patched version as soon as it becomes available. If a patch is not yet available, consider implementing network controls to limit exposure and monitoring for suspicious activities.
For ongoing security, organizations should consider leveraging penetration testing to identify vulnerabilities and validate their security posture.
Detection Guidance
Organizations should monitor logs for any anomalies related to FreeType usage, specifically looking for signs of exploitation or unusual behavior in applications that rely on font parsing.
AppSecure Threat Intelligence Insight
The long-term implications of CVE-2025-27363 suggest a growing trend of vulnerabilities associated with font processing libraries. Security teams should note the potential for similar vulnerabilities in other common libraries and ensure robust security practices are in place.
Organizations are encouraged to integrate learnings from this incident into their vulnerability management program and continually assess their risk landscape.
For a comprehensive understanding of penetration testing methodologies, organizations can refer to the penetration testing methodology which can aid in identifying and mitigating vulnerabilities effectively.
Finally, organizations should keep informed about potential threats by utilizing threat intelligence resources, including insights from AppSecure.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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