CVE-2020-35479 json
MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php.
published 2020-12-18 5 y ago modified 2026-06-17 4 mo ago also BIT-mediawiki-2020-35479 , EUVD-2020-23150
- cvss
- 6.1
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.5%
- EPSS 1.5% chance of exploitation in 30 days, percentile 74%
- public exploits
- 0
- none known
Summary
MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. Language::translateBlockExpiry itself does not escape in all code paths. For example, the return of Language::userTimeAndDate is is always unsafe for HTML in a month value. This affects MediaWiki 1.12.0 and later.
Patch / fix
- bitnami mediawiki 1.35.1
- mediawiki mediawiki 1.35.1
- mediawiki Debian 14, Debian 13, Debian 12 1:1.35.1-1
debian advisories DEBIAN-CVE-2020-35479
- mediawiki Arch Linux 1.35.1-1
arch linux advisories AVG-1371
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-2020-35479 updated cvss 6.1
mediawiki: potential XSS via the month messages such as MediaWiki:january through MediaWiki:december outputting Block Logs
-
Red Hat OpenShift Container Platform 3.11 mediawikiaffected: no fix planned “Will not fix”
-
Red Hat OpenShift Container Platform 4 mediawikiaffected: 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
Exploit prediction
1.49% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- phabricator.wikimedia.org https://phabricator.wikimedia.org/T268938 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:N/I:P/A:N |
| OSV | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | mediawiki | >=1.12.0, <1.35.1 |
1.35.1 |
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
phabricator.wikimedia.org
/T268938
exploit, vendor-advisory, web
-
debian.org
/security/2020/dsa-4816
vendor-advisory, third-party-advisory, web
-
lists.fedoraproject.org
/archives/list/package-announce%40lists.fedoraproject.org/message/STT5Z4A3BCXVH3WIPICWU2FP4IPIMUPC/
vendor-advisory, web
-
lists.wikimedia.org
/pipermail/mediawiki-announce/2020-December/000268.html
mailing-list, release-notes, vendor-advisory, web
-
lists.debian.org
/debian-lts-announce/2020/12/msg00034.html
mailing-list, third-party-advisory, web
-
nvd.nist.gov
/vuln/detail/CVE-2020-35479
web
Sources
- CVE List CVE-2020-35479
- NVD CVE-2020-35479
- OSV BIT-mediawiki-2020-35479
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.