Review reviewHigh

CVE-2026-48788

umputun remark42

Remark42 is a self-hosted comment engine for blogs, articles, or any other place where readers can add comments. Versions 1.6.0 through 1.15.0 contain a Cross-Site Scripting (XSS) vulnerability exploitable through content-type spoofing. The Remark42 image proxy fetches an arbitrary remote URL and re-serves the response from Remark42's own origin. During the download phase, the proxy determines whether the resource is an image by inspecting only the Content-Type header advertised by the remote server, never examining the actual bytes; during the serving phase, it instead derives the response...

CVSS: 8.2
EPSS: 0.25%
CISA KEV: Not listed
Published: 2026.06.17

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.25%

Technical severityCVSS 8.2

Vulnerability overview

Affected product and versions

Product: umputun remark42
Affected versions: >= 1.6.0, < 1.16.0
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that umputun remark42 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
CWE: CWE-436, CWE-79