VulnerabilityPublished 23 Oct 2025Updated 24 Oct 2025

CVE-2025-50951: fontforge · Memory Leak

Affects fontforgeSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
GitHubfontforge/fontforge`pkg:github/fontforge/fontforge`Other threats	Affected =20230101	Fixed in–

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AI-suggested

Monitor official FontForge repositories and security advisories closely for patches addressing CVE-2025-50951 and apply updates promptly once available.
Restrict access to FontForge applications and font processing services to trusted users only, minimizing exposure to untrusted font files.
Implement strict validation and sandboxing of font files before processing to detect and isolate potentially malicious inputs.
Educate users about the risks of opening font files from untrusted sources to reduce the likelihood of user interaction-based exploitation.
Employ memory usage monitoring and alerting on systems running FontForge to detect abnormal memory consumption indicative of exploitation attempts.
Consider using alternative font editing tools temporarily if feasible, especially in critical production environments.
For automated pipelines, introduce additional scanning or filtering steps to identify malformed or suspicious font files prior to processing.
Maintain robust backup and recovery procedures to minimize operational impact in case of denial of service incidents.

Description

FontForge v20230101 was discovered to contain a memory leak via the utf7toutf8_copy function at /fontforge/sfd.c.

Impact

For European organizations, the primary impact of CVE-2025-50951 is on availability. Organizations that utilize FontForge for font editing, graphic design, or software development may experience application crashes or system instability if a maliciously crafted font file exploiting this memory leak is processed. This could disrupt workflows, delay publishing or software releases, and potentially impact services that rely on automated font processing. While the vulnerability does not compromise confidentiality or integrity, denial of service conditions can lead to operational downtime and increased support costs. Sectors such as media, publishing, advertising, and software development in Europe are particularly at risk. Additionally, organizations that integrate FontForge into automated pipelines or web services may face broader service interruptions. Given that exploitation requires user interaction, social engineering or phishing campaigns could be used to trick users into opening malicious font files, increasing the risk vector. The absence of patches means that organizations must rely on compensating controls until an official fix is available.

CWE-401Missing Release of Memory after Effective Lifetime (opens in a new tab)
Variant weaknessLikelihood of exploit: Medium
The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
Implementation · Libraries or Frameworks
Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Architecture and Design · Build and Compilation
Consider using the Boehm-Demers-Weiser garbage collector (bdwgc), which can help avoid leaks.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/fontforge/fontforge/pull/5495 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 31 Oct 2025, 07:36 UTC

WeaknessesCWE-401

Technical details

References

Community reviews

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