Security Digest · Vulnerability record
CVE-2026-41901: Sandboxed Thymeleaf expressions vulnerable to improper recognition of unauthorized syntax patterns
Thymeleaf is a server-side Java template engine for web and standalone environments.
CVSS 9.0 Critical EPSS 0.5% · p45
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- 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.
From the GitHub advisory
Impact
A security bypass vulnerability exists in the expression execution mechanisms of Thymeleaf up to and including 3.1.4.RELEASE. 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).
Patches
This has been fixed in Thymeleaf 3.1.5.RELEASE. All users are advised to upgrade immediately.
Workarounds
Weakness type: CWE-917, CWE-1336.
Product: org.thymeleaf:thymeleaf (Maven) · Assigned by: GitHub_M · Published: 2026-05-12
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Maven | org.thymeleaf:thymeleaf | <= 3.1.4.RELEASE | 3.1.5.RELEASE |
| Maven | org.thymeleaf:thymeleaf-spring5 | <= 3.1.4.RELEASE | 3.1.5.RELEASE |
| Maven | org.thymeleaf:thymeleaf-spring6 | <= 3.1.4.RELEASE | 3.1.5.RELEASE |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| thymeleaf | thymeleaf | < 3.1.5.RELEASE |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9 Critical | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| GitHub | 3.1 | 9.0 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: high (needs special conditions)
- Privileges required: none (no login)
- User interaction: none
- Scope: changed (can affect other components)
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- 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.
Timeline
- — GitHub-reviewed advisory GHSA-c9ph-gxww-7744 published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-c9ph-gxww-7744 github.com
- CVE.org record CVE-2026-41901 cve.org
- NVD entry CVE-2026-41901 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com