Answer in brief
CVE-2026-40478 records a Critical severity (CVSS 9.0) vulnerability in Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf. The current sources do not mark it as known exploited. The current feed maps thymeleaf/org.thymeleaf:thymeleaf-spring5 (generic), thymeleaf/org.thymeleaf:thymeleaf-spring6 (generic), thymeleaf/thymeleaf (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps thymeleaf/org.thymeleaf:thymeleaf-spring5 (generic), thymeleaf/org.thymeleaf:thymeleaf-spring6 (generic), thymeleaf/thymeleaf (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:thymeleaf:thymeleaf:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| thymeleaf/org.thymeleaf:thymeleaf-spring5generic | < 3.1.4.RELEASE | Not reported |
| thymeleaf/org.thymeleaf:thymeleaf-spring6generic | < 3.1.4.RELEASE | Not reported |
| thymeleaf/thymeleafgeneric | < 3.1.4.RELEASE | Not reported |
Published upstream
Apr 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
Thymeleaf is a server-side Java template engine for web and standalone environments. Versions 3.1.3.RELEASE and prior contain a security bypass vulnerability in the the expression execution mechanisms. Although the library provides mechanisms to prevent expression injection, it fails to properly neutralize specific syntax patterns that allow for the execution of unauthorized expressions. If an application developer passes unvalidated user input directly to the template engine, an unauthenticated remote attacker can bypass the library's protections to achieve Server-Side Template Injection (SSTI). This issue has ben fixed in version 3.1.4.RELEASE.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-40478 records a Critical severity (CVSS 9.0) vulnerability in Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf. The current sources do not mark it as known exploited. The current feed maps thymeleaf/org.thymeleaf:thymeleaf-spring5 (generic), thymeleaf/org.thymeleaf:thymeleaf-spring6 (generic), thymeleaf/thymeleaf (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps thymeleaf/org.thymeleaf:thymeleaf-spring5 (generic), thymeleaf/org.thymeleaf:thymeleaf-spring6 (generic), thymeleaf/thymeleaf (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:thymeleaf:thymeleaf:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| thymeleaf/org.thymeleaf:thymeleaf-spring5generic | < 3.1.4.RELEASE | Not reported |
| thymeleaf/org.thymeleaf:thymeleaf-spring6generic | < 3.1.4.RELEASE | Not reported |
| thymeleaf/thymeleafgeneric | < 3.1.4.RELEASE | Not reported |
Published upstream
Apr 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 15, 2026
Thymeleaf is a server-side Java template engine for web and standalone environments. Versions 3.1.3.RELEASE and prior contain a security bypass vulnerability in the the expression execution mechanisms. Although the library provides mechanisms to prevent expression injection, it fails to properly neutralize specific syntax patterns that allow for the execution of unauthorized expressions. If an application developer passes unvalidated user input directly to the template engine, an unauthenticated remote attacker can bypass the library's protections to achieve Server-Side Template Injection (SSTI). This issue has ben fixed in version 3.1.4.RELEASE.
Quoted source text, attributed separately from HOL analysis.