CVE-2026-91852: Apache Sling XSS: CWE-79 multiple raw-string break-outs and ReDOS in XSSImpl

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-23 · updated 2026-09-30
Weakness: CWE-79

Description

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Apache Sling XSS. This issue affects Apache Sling XSS: before 2.4.12. Users are recommended to upgrade to version 2.4.12, which fixes the issue.

Affected products

Apache Software Foundation Apache Sling XSS: before 2.4.12 — fixed in 2.4.12

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache Sling XSS 2.4.12. Check the vendor advisory for mitigations.

References

https://lists.apache.org/thread/nd0ncdk5qb9gqvn0s10rmhnbk887k1qo
https://sling.apache.org/news.html
http://www.openwall.com/lists/oss-security/2026/09/23/12

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