CVE-2011-1579

CVE-2011-1579 is a medium-severity vulnerability in Mediawiki with a CVSS 2.0 base score of 5.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

• Severity: Medium (CVSS 2.0 base score 5.8)
• EPSS exploit prediction: 2% (77th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-20
• Affected product: Mediawiki
• Published: 2011-04-27
• Last modified: 2026-06-16

Description

The checkCss function in includes/Sanitizer.php in the wikitext parser in MediaWiki before 1.16.3 does not properly validate Cascading Style Sheets (CSS) token sequences, which allows remote attackers to conduct cross-site scripting (XSS) attacks or obtain sensitive information by using the \2f\2a and \2a\2f hex strings to surround CSS comments.

Frequently asked questions

What is CVE-2011-1579?

The checkCss function in includes/Sanitizer.php in the wikitext parser in MediaWiki before 1.16.3 does not properly validate Cascading Style Sheets (CSS) token sequences, which allows remote attackers to conduct cross-site scripting (XSS) attacks or obtain sensitive information by using the \2f\2a and \2a\2f hex strings to surround CSS comments.

How severe is CVE-2011-1579?

CVE-2011-1579 has a CVSS 2.0 base score of 5.8, rated medium severity.

Is CVE-2011-1579 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-1579?

CVE-2011-1579 primarily affects Mediawiki. In total, 135 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-1579?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2011-1579 published?

CVE-2011-1579 was published on 2011-04-27 and last updated on 2026-06-16.

References

• http://lists.fedoraproject.org/pipermail/package-announce/2011-April/058588.html
• http://lists.fedoraproject.org/pipermail/package-announce/2011-April/058910.html
• http://lists.fedoraproject.org/pipermail/package-announce/2011-April/059232.html
• http://lists.fedoraproject.org/pipermail/package-announce/2011-April/059235.html
• http://lists.wikimedia.org/pipermail/mediawiki-announce/2011-April/000096.html
• http://openwall.com/lists/oss-security/2011/04/13/15
• http://secunia.com/advisories/44142
• http://www.debian.org/security/2011/dsa-2366
• http://www.mediawiki.org/wiki/Special:Code/MediaWiki/85856
• http://www.securityfocus.com/bid/47354
• http://www.vupen.com/english/advisories/2011/0978
• http://www.vupen.com/english/advisories/2011/1100
• http://www.vupen.com/english/advisories/2011/1151
• https://bugzilla.redhat.com/show_bug.cgi?id=695577
• https://bugzilla.redhat.com/show_bug.cgi?id=696360
• https://bugzilla.wikimedia.org/show_bug.cgi?id=28450
• https://exchange.xforce.ibmcloud.com/vulnerabilities/66738

Affected products (135)

• cpe:2.3:a:mediawiki:mediawiki:*:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.2.0:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.2.2:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.2.3:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.2.4:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.2.5:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.2.6:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.0:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.1:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.2:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.3:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.4:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.5:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.6:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.7:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.8:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.9:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.10:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.11:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.12:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.13:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.14:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.3.15:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4:beta1:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4:beta2:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4:beta3:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4:beta4:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4:beta5:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4:beta6:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.0:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.1:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.2:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.3:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.4:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.5:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.6:*:*:*:*:*:*:*
• cpe:2.3:a:mediawiki:mediawiki:1.4.7:*:*:*:*:*:*:*

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