# CVE-2026-77609: Semantic MediaWiki has an open redirect in Special:URIResolver

> CVE-2026-77609 (GitHub advisory GHSA-hw3m-8j5x-94ff) is a medium-severity vulnerability with a CVSS 3.1 base score of 6.1, classed as URL Redirection to Untrusted Site ('Open Redirect') (CWE-601), in mediawiki/semantic-media-wiki (Packagist). Affected versions: <= 7.1.0. It is fixed in 7.2.0.

Canonical page: https://cveminer.com/vulnerabilities/CVE-2026-77609

| Field | Value |
| --- | --- |
| CVE | CVE-2026-77609 |
| GHSA | GHSA-hw3m-8j5x-94ff |
| Severity | Medium |
| CVSS 3.1 | 6.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N` (GitHub Advisory Database) |
| CWE | CWE-601 URL Redirection to Untrusted Site ('Open Redirect') |
| EPSS | 0.14% (higher than 4% of CVEs) |
| CISA KEV | Not listed |
| Published | 18 Sept 2026 |
| Modified | 18 Sept 2026 |

## Description

###### Failure mode

`Special:URIResolver` resolves its user-controlled subpage to a MediaWiki title and issues an HTTP 303 redirect to `$title->getFullURL()` without validating the resolved target. A crafted subpage can make that target point off-host: an interwiki prefix redirects to the foreign wiki (for example `Special:URIResolver/mw-3AFoo`, which decodes to `mw:Foo`, redirects to `https://www.mediawiki.org/wiki/Foo`), and where the resolved URL carries an authority the target can even embed `user:pass@host` credentials. The result is an open redirect to an attacker-influenced host, usable for phishing from a trusted wiki URL.

###### Remediation

- The resolved target URL is parsed and compared against the current host at the redirect sink.
- The redirect is rejected (bad-title error page) when a user or pass component is present, or when the host does not match the current host.

###### Maintenance note

Redirect code must validate the final target URL, not just the input path. Host comparison belongs at the redirect sink: each sink (special page, entry point) must validate its own target rather than relying on upstream normalisation.

## Affected packages

| Package | Ecosystem | PURL | Vulnerable versions | Fixed in |
| --- | --- | --- | --- | --- |
| mediawiki/semantic-media-wiki | Packagist | `pkg:composer/mediawiki/semantic-media-wiki` | <= 7.1.0 | 7.2.0 |

## Fix commits

- Release: https://github.com/semanticmediawiki/semanticmediawiki/commit/0d11c070bbe64f4425e3ab8be89eefa926dd9e4e (7.2.0)

## Questions

**What is the GHSA ID for CVE-2026-77609?**

GitHub tracks CVE-2026-77609 as GHSA-hw3m-8j5x-94ff.

**What is the CVSS score of CVE-2026-77609?**

CVE-2026-77609 has a CVSS 3.1 base score of 6.1 (Medium), vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

**Which versions are affected by CVE-2026-77609?**

mediawiki/semantic-media-wiki (Packagist): <= 7.1.0.

**How do I fix CVE-2026-77609?**

Upgrade to 7.2.0 or later.

**What is the Package URL (PURL) for CVE-2026-77609?**

The affected package's PURL is pkg:composer/mediawiki/semantic-media-wiki.

**Is CVE-2026-77609 exploited in the wild?**

CISA's Known Exploited Vulnerabilities catalog doesn't list CVE-2026-77609. That means no confirmed exploitation has been catalogued, not that it is safe to leave unpatched. EPSS estimates a 0.14% chance of exploitation in the next 30 days, higher than 4% of CVEs.

## References

- https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-hw3m-8j5x-94ff (advisory)
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77609.json (advisory)
- https://nvd.nist.gov/vuln/detail/CVE-2026-77609 (advisory)
- https://github.com/advisories/GHSA-hw3m-8j5x-94ff (advisory)
- https://github.com/SemanticMediaWiki/SemanticMediaWiki (package)
- https://github.com/SemanticMediaWiki/SemanticMediaWiki/releases/tag/7.2.0

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Source: CVEminer (https://cveminer.com/vulnerabilities/CVE-2026-77609), compiled from OSV (GitHub advisory), GitHub Advisory Database, OSV (CVE record), CVE.org, CISA KEV catalog. OSV and GitHub Advisory Database content is licensed CC BY 4.0.