Vulnerability Description
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
Related Weaknesses (CWE)
References
- https://cert.pl/en/posts/2026/08/CVE-2026-71391
- https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=95ab9ef627b212d74d321c5bb
- https://www.gnu.org/savannah-checkouts/gnu/emacs/emacs.html
FAQ
What is CVE-2026-71391?
CVE-2026-71391 is a documented vulnerability. 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 ...
How severe is CVE-2026-71391?
CVSS scoring is not yet available for CVE-2026-71391. Check NVD for updates.
Is there a patch for CVE-2026-71391?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.