CVE-2026-78847Public exploit

Code execution via JavaScript front matter eval

Published Sep 21, 2026 · Updated Sep 21, 2026

Code injection in gray-matter 4.0.3 allows attackers to execute arbitrary code when an application parses crafted JavaScript front matter. The JavaScript engine in lib/engines.js selects the language from the front-matter delimiter and passes the enclosed text to eval(). Exposure requires an application to pass attacker-controlled content to matter(), and successful execution runs with that application's privileges.

CVSS severityUnavailable
Unscored
EPSS probability0.60%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in gray-matter 4.0.3 allows attackers to execute arbitrary code when an application parses crafted JavaScript front matter. The JavaScript engine in lib/engines.js selects the language from the front-matter delimiter and passes the enclosed text to eval(). Exposure requires an application to pass attacker-controlled content to matter(), and successful execution runs with that application's privileges.

The record

CVE
CVE-2026-78847
Published
Sep 21, 2026
Updated
Sep 21, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-94, T1059.007
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1059.007JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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