5.3

CVE-2026-71391: gnu emacs Off-by-one Error

CVSS: 5.3v4.0MediumDeferred
AliasesUBUNTU-CVE-2026-71391DEBIAN-CVE-2026-71391
Published 10-08-2026Last modified 10-08-2026
Open JSON

Vulnerability summary

CVE-2026-71391 is a medium (CVSS 5.3) Off-by-one Error vulnerability in gnu emacs. EPSS estimates a 0.54% chance of exploitation in the next 30 days, higher than 44.4% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.54%
0%100%
Low · +0.22 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 10-08-2026
    PublishedVulnerability first disclosed.
  2. 10-08-2026
    Last modifiedVulnerability information updated.

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

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.54%

Chance of exploitation in the next 30 days

Percentile

44%

Versus all other CVEs

30-day change

+0.22 pp

From 0.33% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.54%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu5 products
  • emacsAll versions (No fix recorded)
  • emacs24All versions (No fix recorded)
  • emacs25All versions (No fix recorded)
  • xemacs21All versions (No fix recorded)
  • xemacs21-packagesAll versions (No fix recorded)
Debian1 product
  • emacsAll versions (No fix recorded)
Gnu1 product

3 vendors · 7 products

References

6 links