CVE-2026-57656Network attack vector

Author-level stored XSS via unsanitized SVG uploads

Published Jun 26, 2026 · Updated Jun 26, 2026

Stored XSS in Peregrine Themes Hester Core 1.1.8 and earlier allows remote authenticated users to execute script through uploaded SVG images. Hester Core stores uploaded SVG image content without the sanitizer later added for image uploads, leaving active script content available for browser rendering. Author-level access and a second user’s interaction are required; script execution occurs in the viewing user’s browser context.

CVSS severity5.9
Medium
EPSS probability0.24%
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 Peregrine Themes Hester Core 1.1.8 and earlier allows remote authenticated users to execute script through uploaded SVG images. Hester Core stores uploaded SVG image content without the sanitizer later added for image uploads, leaving active script content available for browser rendering. Author-level access and a second user’s interaction are required; script execution occurs in the viewing user’s browser context.

The record

CVE
CVE-2026-57656
Published
Jun 26, 2026
Updated
Jun 26, 2026
Vendor
Peregrine Themes
Product
Hester Core
Classifications
CWE-79, CAPEC-592, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 26, 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=n/a <=1.1.8 changes=[{"at":"1.1.9","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Peregrine Themes · Hester Coreversion=n/a <=1.1.8 changes=[{"at":"1.1.9","status":"unaffected"}]

Published CVSS scores

5.9PatchstackCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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')
CAPEC-592Stored XSS
T1059.007JavaScript

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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