CVE-2026-58034: Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in W

Routine

MEDIUM 4.8DOWNGRADE

CVE-2026-58034 is a medium-severity flaw (CVSS 4.8) affecting mediawiki. 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 (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation CheckUser. This vulnerability is associated with program files modules/ext.CheckUser.TempAccounts/components/blockConnectedTempAccountsField.Vue. This issue affects CheckUser: from 1.46.0-rc.0 before 1.46.0.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	4.8 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	Required
EPSS exploit chance	0.3% (top 79%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-07-01
Last modified	2026-10-25

Publisher (CNA): wikimedia-foundation · Vendor: mediawiki

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-01 15:17 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

mediawiki mediawiki DOWNGRADE

Affected: 1.46.0 rc0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.46.0

1. Check installed version

apt-cache policy mediawiki || rpm -q mediawiki || mediawiki --version

2. No fixed release: DOWNGRADE to a release before 1.46.0 (Debian / Ubuntu)

apt-cache madison mediawiki sudo apt install mediawiki=<VERSION_BEFORE_1.46.0> sudo apt-mark hold mediawiki

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mediawiki sudo dnf downgrade mediawiki-<VERSION_BEFORE_1.46.0> sudo dnf versionlock add mediawiki

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2026-58034?

mediawiki: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-58034 being exploited?

CVE-2026-58034 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-2026-58034 affect?

CVE-2026-58034 affects mediawiki. Severity is medium (CVSS 4.8). Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation CheckUser. This vulnerability is associated with program files modules/ext.CheckUser.TempAccounts/components

How urgent is CVE-2026-58034?

Priority 22/100. No elevated risk signals yet.

Related CVEs

CVE-2026-8857 HIGH 8.8 UPGRADE A vulnerability in Wikimedia Foundation timeline. This vulnerability is associated with program files script
CVE-2026-58025 CRITICAL 9.8 UPGRADE Deserialization of untrusted data vulnerability in Wikimedia Foundation MediaWiki. This vulnerability is ass
CVE-2026-13706 HIGH 8.8 UPGRADE Improper input validation vulnerability in Wikimedia Foundation UrlShortener. This vulnerability is associat
CVE-2026-58036 HIGH 7.5 DOWNGRADE Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Wikimedia Foundation MediaWiki.
CVE-2026-58029 MEDIUM 6.5 UPGRADE Vulnerability in Wikimedia Foundation MediaWiki. This vulnerability is associated with program files include

References

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