CVE-2026-48788

What it is

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 Content-Type by sniffing those bytes with http.DetectContentType. An attacker can exploit this inconsistency by hosting a URL that advertises Content-Type: image/png while returning an HTML/JavaScript body: the download check accepts it as an image, the serving path sniffs the body and emits Content-Type: text/html, and the browser renders the attacker-controlled HTML/JavaScript as a document within Remark42's origin. Exploitation requires no Remark42 account on the target instance; the attacker only needs to host the malicious upstream URL and deliver the proxy link to a victim by any means, such as email, direct message, or a link on another website. This issue has been fixed in version 1.16.0.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. High risk of data exposure.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-17 13:20 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-25 23:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 8.2 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-06-17 13:20 UTC

Last modified

2026-10-25 23:10 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-79 · Cross-site scripting

Record status

Deferred

Attack profile CVSS 3.0 · 8.2

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Changed

Confidentiality

High

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-48788.md and follow it. Check whether this project is affected by CVE-2026-48788. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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