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CRITICAL severity

CVE-2026-84939 — freemarker

CRITICALFix: apache/freemarker@83953d9

CVE-2026-84939 is a critical-severity (CVSS 9.1) CWE-23 vulnerability in org.freemarker:freemarker. A fix is available for org.freemarker:freemarker — see the affected versions and patch details below.

Apache FreeMarker template loading mechanism vulnerable to path traversal

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 25, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs58th percentile — riskier than 58% of all scored CVEsHighest risk
0.35%0.69%1.02%1.35%0.9%0.9%Oct 26Oct 26

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

How urgent is this, really

CVE-2026-84939 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,492 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
☕org.freemarker:freemarker

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

Description

Path traversal vulnerability in Apache FreeMarker template loading mechanism, if the attacker can specify an arbitrary malformed locale identifier to FreeMarker, and the localized lookup configuration setting is enabled (it's by default enabled).

This issue affects Apache FreeMarker from 2.2.0 through 2.3.34.

Users are recommended to upgrade to version 2.3.35. Disabling localized lookup in previous versions also mitigates this.

Note that even in versions affected by this vulnerability, the files that can be loaded remain restricted by the TemplateLoader that FreeMarker is configured to use. In particular, FileTemplateLoader prevents attempts to traverse outside the baseDir specified in its constructor. Other TemplateLoader implementations may allow access outside their designated base directory, but they are still constrained by the underlying storage mechanism—for example, a loader wrapping a Java class loader can only access resources that the class loader can load, while one wrapping a web application context can only access resources available through that context.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.freemarker:freemarker≥ 2.2.0&&< 2.3.352.3.35org.freemarker:freemarker:2.3.35

Affected Products

1 product · 1 configurations
Application
freemarkerapache
≥ 2.2 && < 2.3.35
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update org.freemarker:freemarker to 2.3.35 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-84939 is resolved across your whole dependency graph.

  3. Workarounds

    Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This is an Important path traversal vulnerability in Apache FreeMarker, affecting Red Hat JBoss Fuse, Red Hat Build of Keycloak, and Red Hat Single Sign-On. An attacker can exploit this flaw by providing a malformed locale identifier when localized lookup is enabled by default, potentially accessing restricted files.…

Workaround published by Red Hat
To mitigate this vulnerability, disable the localized lookup configuration setting within your Apache FreeMarker deployment. This setting is enabled by default and its deactivation prevents the processing of malformed locale identifiers that could lead to path traversal. Consult your application's documentation for specific instructions on how to configure FreeMarker to disable localized lookup. A restart of the affected application or service will be required for the changes to take effect. Disabling localized lookup may impact applications that rely on this feature for internationalization.
Source: Red Hat security advisory for CVE-2026-84939 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat build of Quarkus 3.27.6.redhatorg.freemarker/freemarker:2.3.35RHSA-2026:83082
Red Hat build of Quarkus 3.33.4.redhatorg.freemarker/freemarker:2.3.35RHSA-2026:83520

Frequently Asked Questions

Path traversal vulnerability in Apache FreeMarker template loading mechanism, if the attacker can specify an arbitrary malformed locale identifier to FreeMarker, and the localized lookup configuration setting is enabled (it's by default enabled). This issue affects Apache FreeMarker from 2.2.0 through 2.3.34. Users are recommended to upgrade to version 2.3.35. Disabling localized lookup in previous versions also mitigates this. Note that even in versions affected by this vulnerability, the files that can be loaded remain restricted by the TemplateLoader that FreeMarker is configured to use.
O3 Security · Impact-Aware SCA

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CVE-2026-84939: freemarker — Fixed in 2.3.35