CVE-2026-91999: Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Apache S

Q: How do I fix CVE-2026-91999?

sling xss protection api: upgrade to 2.4.12. Exact commands for each OS are on this page.

Q: Is CVE-2026-91999 being exploited?

CVE-2026-91999 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-91999 affect?

CVE-2026-91999 affects sling xss protection api. Severity is medium (CVSS 6.1). 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 fixe

Q: How urgent is CVE-2026-91999?

Priority 38/100. On your watchlist

Routine

MEDIUM 6.1WATCHLISTUPGRADE

CVE-2026-91999 is a medium-severity flaw (CVSS 6.1) affecting sling xss protection api. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-09-23
Last modified	2026-09-30

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-09-30 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-23 10:17 UTCPublished CVE record published
2026-09-30 16:11 UTCUpdated Record last modified

apache sling xss protection api UPGRADE

Affected: < 2.4.12

Fixed in: 2.4.12

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy sling-xss-protection-api || rpm -q sling-xss-protection-api || sling-xss-protection-api --version

2. UPGRADE to 2.4.12 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sling-xss-protection-api

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sling-xss-protection-api

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-91999?

sling xss protection api: upgrade to 2.4.12. Exact commands for each OS are on this page.

Is CVE-2026-91999 being exploited?

CVE-2026-91999 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-91999 affect?

CVE-2026-91999 affects sling xss protection api. Severity is medium (CVSS 6.1). 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 fixe

How urgent is CVE-2026-91999?

Priority 38/100. On your watchlist

Related CVEs

CVE-2026-73192 MEDIUM 6.1 UPGRADE An improper neutralization of input during web page generation ('Cross-site Scripting') [CWE-79] vulnerability
CVE-2026-91852 MEDIUM 6.1 UPGRADE Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Apache S
CVE-2026-91928 MEDIUM 6.1 UPGRADE Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Apache S
CVE-2026-92001 MEDIUM 6.1 UPGRADE Improper restriction of recursive entity references in DTDs ('XML entity expansion') vulnerability in Apache S

References

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