YesWiki: Unauthenticated page overwrite via Bazar entry creation
Summary
YesWiki before 4.6.7 lets unauthenticated visitors overwrite the body of any existing wiki page through the Bazar entry-creation flow. Write ACLs do not prevent this, because the entry is saved with ACLs bypassed. An attacker only needs to send a crafted request that names an existing page, which enables mass defacement and content loss. No login or user interaction is required, but the Bazar module must be reachable on the site.
Affected
- YesWiki versions before 4.6.7 (the GHSA advisory lists <= 4.6.6)
- Lower bounds of the affected range are not verified; treat all versions below 4.6.7 as affected
Fixed in
- Upgrade to YesWiki 4.6.7 or later (fixing commit 07120ed8971047f504f7ec78060828f1895f475f)
Workaround
Unknown. No vendor workaround is documented. Interim measure (not from the vendor): restrict access to the Bazar entry-save endpoint at the web server or reverse proxy until 4.6.7 is applied.
Exploitation
- Not listed as known exploited (KEV: No). EPSS 0.00277 (low).
- A public proof of concept is reported by an aggregator but is not verified.
Our recommendation
- Identify all YesWiki instances and their versions.
- Upgrade to 4.6.7 or later and confirm the upgrade against the GHSA advisory.
- Restrict or monitor entry-save requests until patched.
- Check page histories for unexpected changes and verify backups of critical wiki content.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-4388-phmh-jrw8 github.com
- VulnCheck Advisory: YesWiki before 4.6.7 Unauthenticated Page Overwrite www.vulncheck.com
- OSV: CVE-2026-104449 osv.dev
- VulDB: CVE-2026-104449 vuldb.com
- Mend record via Vulners vulners.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 14:18.
Original description (NVD)
YesWiki before 4.6.7 contains an access control vulnerability allowing unauthenticated attackers to overwrite any existing wiki page, including pages whose write ACL restricts editing, via the Bazar entry-creation flow. Attackers can submit a crafted entry with an attacker-controlled id_fiche matching an existing page, overwriting its body for mass defacement and content destruction.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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