CVE-2026-74908Network attack vector

Stored XSS via extension-only SVG sanitization

Published Aug 18, 2026 · Updated Aug 18, 2026

Stored XSS in Grav plugin-api before 1.0.15 allows remote authenticated users to execute script in the site origin via uploaded media files. In HandlesMediaUploads.php, the upload path sanitizes files only when the client-supplied extension is exactly svg, while the dangerous-extension denylist omits svgz and xhtml, so those script-capable formats are written to disk unsanitized. Exploitation requires the api.media.write permission and a later admin or visitor view of the stored file; the demonstrated impact is script execution in the Grav site origin rather than server-side code execution by default.

CVSS severity5.1
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Grav plugin-api before 1.0.15 allows remote authenticated users to execute script in the site origin via uploaded media files. In HandlesMediaUploads.php, the upload path sanitizes files only when the client-supplied extension is exactly svg, while the dangerous-extension denylist omits svgz and xhtml, so those script-capable formats are written to disk unsanitized. Exploitation requires the api.media.write permission and a later admin or visitor view of the stored file; the demonstrated impact is script execution in the Grav site origin rather than server-side code execution by default.

The record

CVE
CVE-2026-74908
Published
Aug 18, 2026
Updated
Aug 18, 2026
Vendor
Grav
Product
Grav
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 18, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.0.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Grav · Gravversion=0 <1.0.15

Published CVSS scores

5.1VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
4.6VulnCheckCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

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.

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

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

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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