CVE-2026-41901
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThymeleaf 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThymeleaf before 3.1.5.RELEASE contains a security bypass in its expression execution mechanisms. The template engine's sandboxed contexts fail to properly neutralize specific expression constructs, allowing Server-Side Template Injection (SSTI) when unsanitized user input containing dangerous expressions is passed to templates.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Thymeleaf versionCheck your project's dependency management file (Maven pom.xml, Gradle build.gradle) or the thymeleaf JAR file META-INF/MANIFEST.MF for the Implementation-Version attributeAffected if Version is lower than 3.1.5.RELEASE (e.g., 3.1.4.RELEASE, 3.1.3.RELEASE, 3.0.x, etc.)
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Verify sandboxed template configuration is in useSearch your codebase for TemplateResolver or Spring template configuration classes that set the sandbox mode flag (typically 'sandbox' or 'SANDBOX_MODE_ENABLED')Affected if Your application uses Thymeleaf's sandbox mode for template rendering but relies on it for security isolation
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Inspect template usage patterns for user inputSearch your controller/service code for calls to templateEngine.process(), templateEngine.parse(), or similar methods where the template name or variables include request parameters, headers, or other user-supplied data (e.g., @RequestParam, HttpServletRequest.getParameter())Affected if Unsantized user input flows directly into template variables or template names passed to Thymeleaf processing methods
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Review expression evaluation in templatesExamine your template files (.html) for Thymeleaf expressions (${...}, *{...}, #{...}) used with data derived from external sourcesAffected if Templates render user-controlled data using Thymeleaf expression syntax without prior sanitization or use of #strings.escapeXml() or similar escaping utilities
You are affected if Thymeleaf version is below 3.1.5.RELEASE AND your application passes unsanitized user input into Thymeleaf templates, particularly within sandboxed contexts relying on expression containment.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade Thymeleaf to version 3.1.5.RELEASE or later. Additionally, audit template code to ensure no unsanitized user input is passed to templates, especially in sandboxed contexts.
3.1.5.RELEASE
- Identify your build management tool (Maven pom.xml or Gradle build.gradle)
- Locate the thymeleaf dependency declaration
- Update the Thymeleaf version to 3.1.5.RELEASE
- For Maven: Change <version> to 3.1.5.RELEASE, for Gradle: change implementation 'org.thymeleaf:thymeleaf:3.x.x' to implementation 'org.thymeleaf:thymeleaf:3.1.5.RELEASE'
- Run mvn clean install or gradle build to fetch the updated dependency
- Test your application thoroughly, particularly any templates using sandboxed contexts with user-provided variables
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-41901 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-41901 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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