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Fencer Vulns
critical 9.0

CVE-2023-3550 json

Stored XSS leads to privilege escalation in MediaWiki v1.40.0

published 2023-09-25 3 y ago modified 2026-06-17 4 mo ago also BIT-mediawiki-2023-3550 , EUVD-2023-44206

cvss
9.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 72%
public exploits
0
none known

Summary

Mediawiki v1.40.0 does not validate namespaces used in XML files.

Therefore, if the instance administrator allows XML file uploads,

a remote attacker with a low-privileged user account can use this

exploit to become an administrator by sending a malicious link to

the instance administrator.

Patch / fix

  • bitnami mediawiki 1.40.1
  • mediawiki Debian 12 1:1.39.5-1~deb12u1
  • mediawiki Debian 14, Debian 13 1:1.39.5-1

debian advisories DEBIAN-CVE-2023-3550

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-3550 updated cvss 7.3

mediawiki: stored XSS leads to privilege escalation

  • Red Hat OpenShift Container Platform 3.11 mediawiki
    affected: no fix planned “Out of support scope”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

1.38% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • fluidattacks.com https://fluidattacks.com/advisories/blondie/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
CNA 3.1 9.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
OSV 3.1 9.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
bitnami mediawiki
>=1.40.0, <1.40.1
1.40.1

Affected products

  • MediaWiki MediaWiki

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.