CVE-2026-71391: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-49vj-r7f8-c3p6
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CWE-193
Published
Advisory Summary

CVE-2026-71391 is a MODERATE security vulnerability vulnerability (CWE-193: Off-by-one Error) affecting Software libraries in the Maven ecosystem. The weakness occurs when a product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-71391 at a Glance

CVE Identifier CVE-2026-71391
GHSA Identifier GHSA-49vj-r7f8-c3p6
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-193: Off-by-one Error
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-71391

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-71391, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-193: Off-by-one Error, where a product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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

References

NVD — CVE-2026-71391 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-71391
cert.pl/en/posts/2026/08/cv... WEB
https://cert.pl/en/posts/2026/08/CVE-2026-71391
git.savannah.gnu.org/cgit/emacs.git/comm... WEB
https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe
www.gnu.org/savannah-checkouts/... WEB
https://www.gnu.org/savannah-checkouts/gnu/emacs/emacs.html

Frequently Asked Questions

What is CVE-2026-71391?
CVE-2026-71391 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-193: Off-by-one Error.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-71391?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-71391?
CVE-2026-71391 is classified under CWE-193: Off-by-one Error (A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.).
How can I check Maven dependencies for CVE-2026-71391?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-49vj-r7f8-c3p6",
  "modified" : "2026-08-10T12:31:51Z",
  "published" : "2026-08-10T12:31:51Z",
  "aliases" : [ "CVE-2026-71391" ],
  "details" : "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.\n\n\nThis issue was fixed in commit 95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-71391"
  }, {
    "type" : "WEB",
    "url" : "https://cert.pl/en/posts/2026/08/CVE-2026-71391"
  }, {
    "type" : "WEB",
    "url" : "https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe"
  }, {
    "type" : "WEB",
    "url" : "https://www.gnu.org/savannah-checkouts/gnu/emacs/emacs.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-193" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-10T11:17:28Z"
  }
}