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CVE-2026-71393: Heap Buffer Overflow in GNU Emacs for Android

• Severity: medium (CVSS 5.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-10 · updated 2026-10-24
• Weakness: CWE-190

Description

GNU Emacs for Android is vulnerable to an integer overflow in sfnt_read_name_table() in src/sfnt.c. The function computes an allocation size using a 32-bit length value from a TrueType font file without overflow checking. On 32-bit targets, a crafted font causes the calculation to wrap, resulting in an undersized heap allocation. A subsequent read() call writes beyond the buffer, causing a heap buffer overflow. 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 can lead to heap memory corruption and potential code execution. This issue was fixed in commit d51a4722316efe0960994d371e1859099894d1ca

Affected products

• GNU Emacs: through 30.2

References

• https://cert.pl/en/posts/2026/08/CVE-2026-71391
• https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=d51a4722316efe0960994d371e1859099894d1ca
• https://www.gnu.org/savannah-checkouts/gnu/emacs/emacs.html

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