Technical impact
An out-of-bounds read occurs in the stbtt_GetGlyphShape routine of the stb library when processing a TrueType font that contains malicious glyph data. This flaw can be triggered by supplying a specially crafted TTF file, resulting in a crash or hang of the application and denying service to legitimate users. The vulnerability is classified as CWE‑125, an out-of-bounds read, and the CVSS score is 4.3, indicating moderate severity.
Affected Systems
No specific vendors or products are named in the advisory. The issue resides in the open‑source stb library, which is used across a variety of software that renders TrueType fonts, so any application embedding this library could be impacted.
Risk and Exploitability
The CVSS score of 4.3 places this flaw in the moderate range, but the lack of an EPSS score and the fact that it is not listed in the CISA KEV catalog suggest exploitation is not yet widely observed. Attackers can leverage the vulnerability by delivering a malicious TTF file to the vulnerable application, either through file uploads or by manipulating font data embedded in documents. The resulting denial of service can affect availability but does not compromise confidentiality or integrity.
