CVE-2026-84939: freemarker Path Traversal — Fix

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.

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CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0083

Probability of exploitation

0.56%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-23 CWE-23

Affected Products

Vendor	Product	Versions
apache	freemarker	2.2 — 2.3.35

References

Advisories & Patches

https://lists.apache.org/thread/hrd7o2ylwkkswdyhyzllgqt0f80kyd5y

Other References

http://www.openwall.com/lists/oss-security/2026/09/08/2

Frequently Asked Questions

What is CVE-2026-84939? +

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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-84939? +

CVE-2026-84939 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0083, placing it in the 1th percentile for exploitation probability.

What products are affected by CVE-2026-84939? +

CVE-2026-84939 affects products from apache, specifically: freemarker. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-84939? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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