CVE-2026-33517: Mantis Bug Tracker (MantisBT) is an open source issue tracker

Routine

MEDIUM 6.1DOWNGRADE

CVE-2026-33517 is a medium-severity flaw (CVSS 6.1) affecting mantisbt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Mantis Bug Tracker (MantisBT) is an open source issue tracker. In version 2.28.0, when deleting a Tag (tag_delete.php), improper escaping of its name when displaying the confirmation message allows an attacker to inject HTML and, if CSP settings permit, achieve execution of arbitrary JavaScript. Version 2.28.1 fixes the issue. Workarounds include reverting commit d6890320752ecf37bd74d11fe14fe7dc12335be9 and/or manually editing language files to r

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 84%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-03-23
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: mantisbt

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-23 20:16 UTCPublished CVE record published
2026-06-17 10:37 UTCUpdated Record last modified

mantisbt mantisbt DOWNGRADE

Affected: 2.28.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.28.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.28.0 (Debian / Ubuntu)

apt-cache madison mantisbt sudo apt install mantisbt=<VERSION_BEFORE_2.28.0> sudo apt-mark hold mantisbt

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

dnf --showduplicates list mantisbt sudo dnf downgrade mantisbt-<VERSION_BEFORE_2.28.0> sudo dnf versionlock add mantisbt

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-2026-33517?

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

Is CVE-2026-33517 being exploited?

CVE-2026-33517 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-2026-33517 affect?

CVE-2026-33517 affects mantisbt. Severity is medium (CVSS 6.1). Mantis Bug Tracker (MantisBT) is an open source issue tracker. In version 2.28.0, when deleting a Tag (tag_delete.php), improper escaping of its name when displaying the confirmation message allows an attacker to inject HTML and, if CSP set

How urgent is CVE-2026-33517?

Priority 25/100. No elevated risk signals yet.

Software pages

PHP vulnerabilities

Related CVEs

CVE-2026-33548 MEDIUM 6.1 DOWNGRADE Mantis Bug Tracker (MantisBT) is an open source issue tracker
CVE-2026-30849 CRITICAL 9.8 UPGRADE Mantis Bug Tracker (MantisBT) is an open source issue tracker

References

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