# CVE-2026-126563: Semantic MediaWiki 2.4.0 before 7.4.1 Reflected XSS via Special:Ask Date Format

> Unauthenticated attackers can craft Special:Ask URLs that run script in logged-in Semantic MediaWiki users' browsers.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Harmful if only installed:** No
- **Needs a specific call:** No
- **Fix available:** No
- **Published:** 11 Nov 2026
- **Updated:** 11 Nov 2026
- **Also known as:** GHSA-h252-mj7p-58q7, GHSA-p9g7-73wv-cwgh

## What is CVE-2026-126563?

CVE-2026-126563 is a medium-severity cross-site scripting vulnerability in SemanticMediaWiki, published on 11 Nov 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Semantic MediaWiki 2.4.0 before 7.4.1 contains a reflected cross-site scripting vulnerability in TimeValueFormatter::getCaptionFromFreeFormat(), which emits free-format date captions in HTML without escaping. Unauthenticated attackers can craft a Special:Ask URL with HTML markup in a date printout format (#-F[...]) to execute script in a logged-in victim's browser session.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-126563?

An affected version is exposed as installed. No special setting or call is needed.


## How do I fix CVE-2026-126563?

No fix has been published for CVE-2026-126563 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-126563 being exploited?

There is no known exploitation of CVE-2026-126563 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-126563 and fix it if it is affected.

What it is: CVE-2026-126563 is a medium-severity cross-site scripting vulnerability in SemanticMediaWiki, published on 11 Nov 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-126563 in the wild and no public exploit code.
Exposure: An affected version is exposed as installed. No special setting or call is needed.

Affected product: SemanticMediaWiki. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-126563/ (Markdown: https://insights.sbomify.com/CVE-2026-126563/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-126563
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126563
- OSV: https://osv.dev/vulnerability/CVE-2026-126563

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-126563/
Summaries are generated and may contain mistakes; the official description above is the record.