CVE-2026-71391
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk25th percentile - higher than 25% of all known CVEs
Summary
GNU Emacs for Android contains an off-by-one error in the gvar table parser in src/sfnt.c. The shared-coordinate index boundary check in sfnt_vary_simple_glyph() and sfnt_vary_compound_glyph() uses a strict greater-than comparison instead of greater-than-or-equal, allowing a crafted TrueType variable font to bypass the check and trigger a heap-based out-of-bounds read via memcpy. This exposes heap memory contents which can be later used to defeat ASLR.
Risk Assessment
An attacker can deliver a malicious font file, potentially leading to disclosure of heap memory contents, which can be used to bypass security mechanisms such as ASLR.
Recommendation
Update GNU Emacs to a version containing commit 95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe or later. Avoid opening untrusted font files.
Original NVD description (English source)
GNU Emacs for Android contains an off-by-one error in the gvar table parser in src/sfnt.c. The shared-coordinate index boundary check in sfnt_vary_simple_glyph() and sfnt_vary_compound_glyph() uses a strict greater-than comparison instead of greater-than-or-equal, allowing a crafted TrueType variable font to bypass the check and trigger a heap-based out-of-bounds read via memcpy. An attacker can deliver a malicious font file via email, EWW (Emacs Web Wowser), or documents with custom faces, causing Emacs to load it. This exposes heap memory contents which can be later used to defeat ASLR. This issue was fixed in commit 95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe