---
title: "CVE-2026-41901: Sandboxed Thymeleaf expressions vulnerable to improper recognition of unauthorized syntax patterns"
url: https://erroneo.us/security/cve/CVE-2026-41901/
description: "CVE-2026-41901 (org.thymeleaf:thymeleaf (Maven)): Thymeleaf is a server-side Java template engine for web and standalone environments. Prior to…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-12
date_modified: 2026-05-13
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-41901"
kev: false
cvss: 9
epss: 0.00544
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-41901: Sandboxed Thymeleaf expressions vulnerable to improper recognition of unauthorized syntax patterns

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5% , percentile 45: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 45% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes org.thymeleaf:thymeleaf (Maven) <= 3.1.4.RELEASE, fixed in 3.1.5.RELEASE ; org.thymeleaf:thymeleaf-spring5 (Maven) <= 3.1.4.RELEASE, fixed in 3.1.5.RELEASE ; org.thymeleaf:thymeleaf-spring6 (Maven) <= 3.1.4.RELEASE, fixed in 3.1.5.RELEASE . Check your lockfile, including transitive dependencies.

## What it is

Thymeleaf is a server-side Java template engine for web and standalone environments. Prior to 3.1.5.RELEASE, a security bypass vulnerability exists in the expression execution mechanisms of Thymeleaf. Although the library provides mechanisms to avoid the execution of potentially dangerous expressions in some specific sandboxed (restricted) contexts, it fails to properly neutralize specific constructs that allow this kind of expressions to be executed. If an application developer passes to the template engine unsanitized variables that contain such expressions, and these values are used in sandboxed contexts inside the templates, these expressions can be executed achieving Server-Side Template Injection (SSTI). This vulnerability is fixed in 3.1.5.RELEASE.

## Affected packages

- Maven `org.thymeleaf:thymeleaf` <= 3.1.4.RELEASE → fixed: 3.1.5.RELEASE
- Maven `org.thymeleaf:thymeleaf-spring5` <= 3.1.4.RELEASE → fixed: 3.1.5.RELEASE
- Maven `org.thymeleaf:thymeleaf-spring6` <= 3.1.4.RELEASE → fixed: 3.1.5.RELEASE

## Affected products (CVE record)

- thymeleaf thymeleaf: < 3.1.5.RELEASE

## Severity

- GitHub_M CVSS 3.1: 9 `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.0 `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.54% probability of exploitation activity in the next 30 days; percentile 45.

## Sources

- [GitHub Advisory GHSA-c9ph-gxww-7744](https://github.com/advisories/GHSA-c9ph-gxww-7744)
- [CVE.org record CVE-2026-41901](https://www.cve.org/CVERecord?id=CVE-2026-41901)
- [NVD entry CVE-2026-41901](https://nvd.nist.gov/vuln/detail/CVE-2026-41901)
- [github.com](https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-c9ph-gxww-7744)

---
Source page: https://erroneo.us/security/cve/CVE-2026-41901/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt