How severe is CVE-2026-34754?

CVE-2026-34754 has a CVSS score of 4.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-34754?

CVE-2026-34754 affects the following packages: mantisbt/mantisbt (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-34754?

Update mantisbt/mantisbt to 2.28.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34754 is resolved across your whole dependency graph.

How do I detect CVE-2026-34754 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mantisbt/mantisbt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-34754 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-34754 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-34754 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-34754?

CVE-2026-34754 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 16th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-34754?

CVE-2026-34754 is classified as CWE-284 (CWE-284). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-34754 published, and has it been updated?

CVE-2026-34754 was published on May 19, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2026-34754 — mantisbt

MEDIUMFix: mantisbt/mantisbt@b262b4d

CVE-2026-34754 is a medium-severity (CVSS 4.3) CWE-284 vulnerability in mantisbt/mantisbt. A fix is available for mantisbt/mantisbt — see the affected versions and patch details below.

MantisBT allows unauthorized users to upload attachments to restricted issues via REST API

Also known asGHSA-h4x5-gvx6-3rwc

Published

May 19, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34754.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs16th percentile — riskier than 16% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘mantisbt/mantisbt

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Impact

MantisBT allows an authenticated user to upload attachments to private Issues they are not authorized to access.

Patches

b262b4d2835b81394d75356dead66e52a6275206

Workarounds

None.

Credits

Thanks to Vishal Shukla for discovering and responsibly reporting the issue.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`mantisbt/mantisbt`	all versions	2.28.2`composer require mantisbt/mantisbt:^2.28.2`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mantisbt/mantisbt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mantisbt/mantisbt to 2.28.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34754 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Impact MantisBT allows an authenticated user to upload attachments to private Issues they are not authorized to access. ### Patches - b262b4d2835b81394d75356dead66e52a6275206 ### Workarounds None. ### Credits Thanks to Vishal Shukla for discovering and responsibly reporting the issue.