---
id: "CVE-2026-126498"
page: "https://infrastack.ai/live/CVE-2026-126498"
kind: "vulnerability"
aliases: ["CVE-2026-126498"]
title: "WriteFreely: stored XSS via post slug runs script for readers"
severity: "medium"
cvss: 5.4
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "WriteFreely", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["activitypub", "other", "rss", "self-hosted", "writefreely"]
not_affected_if: ["no-untrusted-authors", "version-0.17.3-or-later"]
published_at: "2026-11-11T01:17:14+00:00"
first_seen_at: "2026-11-11T01:24:34+00:00"
updated_at: "2026-11-11T01:25:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126498", "first_seen_at": "2026-11-11T01:24:34+00:00"}]
exploit_sources: []
---

# WriteFreely: stored XSS via post slug runs script for readers

Link for people: https://infrastack.ai/live/CVE-2026-126498 (this .md is for agents)

WriteFreely before 0.17.3 lets an authenticated author inject HTML through a malicious post slug sent to the CreatePost API. The raw slug is placed into a link for paid-shortcode posts, so script runs for RSS and Atom feed readers, newsletter recipients and ActivityPub viewers.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:WriteFreely affected range not listed fixed no fixed version listed

## How to check

- Check the installed WriteFreely version; affected if it is below `0.17.3`.
- Review posts that use the paid shortcode for unusual slugs containing HTML or script.

## Fix

- WriteFreely: move to `0.17.3` or later.

## Timeline

- 2026-11-11T01:24:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-126498

## Documents

- [advisory] Vendor advisory: github.com https://github.com/writefreely/writefreely/security/advisories/GHSA-cwxm-8ch5-j2vh
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/writefreely-before-0.17.3-stored-xss-via-unsanitized-post-slug
- [fix] Patch: github.com https://github.com/writefreely/writefreely/commit/d7231d81a914f1314a218d5e8fde6e0341391ccd
- [fix] Release notes: github.com https://github.com/writefreely/writefreely/releases/tag/v0.17.3

## From the sources

WriteFreely before 0.17.3 contains a stored cross-site scripting vulnerability that allows authenticated authors to inject HTML by supplying a malicious post slug via the CreatePost API. The raw slug is concatenated into an anchor by augmentReadingDestination() for paid-shortcode posts, executing script for RSS/Atom feed readers, newsletter recipients and ActivityPub viewers.

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