CVE-2026-40478

CRITICALPre-NVD 9.09.1▲
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit probability: 0.8%, top 48% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: cna:github_m, epss
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.2%CVSS: 9.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
9.0
EG Score
9.1CRITICALmedium confidence
EG Risk
41
EG Risk 41/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation1% × 40%
Automatability0% × 15%
EPSS PROB
1.2%
EPSS %ILE
67th
KEV
Not listed

Published

April 17, 2026

Last Modified

August 18, 2026

Advisory Details (1)

Auto-updated May 2, 2026
Patch available. Sources: github.
githubMentions a patch (unverified)

Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf · Advisory · thymeleaf/thymeleaf · GitHub

https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-xjw8-8c5c-9r79

Vendor Advisories for CVE-2026-40478(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatdevspaces/pluginregistry-rhel9:17793594232026-05-28redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(3 across 1 ecosystem)
Maven(3)
PackageVulnerable rangeFix by version rangeDependents
org.thymeleaf:thymeleaf1.0.0 ... m1 (81 versions)
  • every version up to 3.1.4.RELEASE: fixed in 3.1.4.RELEASE
—
org.thymeleaf:thymeleaf-spring53.0.10.RELEASE ... 3.1.3.RELEASE (22 versions)
  • every version up to 3.1.4.RELEASE: fixed in 3.1.4.RELEASE
—
org.thymeleaf:thymeleaf-spring63.1.0.M1 ... 3.1.3.RELEASE (9 versions)
  • every version up to 3.1.4.RELEASE: fixed in 3.1.4.RELEASE
—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 25× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 264 total refreshes for this CVE.

  1. 2026-10-09 20:07 UTCEPSS rescore
  2. 2026-10-08 17:12 UTCEPSS rescore
  3. 2026-10-07 23:48 UTCEPSS rescore
  4. 2026-10-06 15:17 UTCEPSS rescore
  5. 2026-10-05 17:43 UTCEPSS rescore
  6. 2026-10-04 23:22 UTCEPSS rescore
  7. 2026-10-03 14:25 UTCEPSS rescore
  8. 2026-10-01 19:50 UTCEPSS rescore
  9. 2026-09-30 15:03 UTCEPSS rescore
  10. 2026-09-27 13:48 UTCEPSS rescore
  11. 2026-09-26 15:58 UTCEPSS rescore
  12. 2026-09-24 07:56 UTCOSV refresh
  13. 2026-09-23 17:53 UTCEPSS rescore
  14. 2026-09-20 20:15 UTCEPSS rescore
  15. 2026-09-18 19:28 UTCEPSS rescore
  16. 2026-09-18 19:28 UTCEPSS rescore
  17. 2026-09-17 19:30 UTCEPSS rescore
  18. 2026-09-16 14:08 UTCEPSS rescore
  19. 2026-09-16 05:15 UTCEPSS rescore
  20. 2026-09-15 03:11 UTCEPSS rescore
  21. 2026-09-13 16:47 UTCEPSS rescore
  22. 2026-09-12 15:01 UTCEPSS rescore
  23. 2026-09-11 14:53 UTCEPSS rescore
  24. 2026-09-11 09:37 UTCEPSS rescore
  25. 2026-09-10 09:34 UTCEPSS rescore
Show 75 more
  1. 2026-09-08 22:00 UTCEPSS rescore
  2. 2026-09-07 16:01 UTCEPSS rescore
  3. 2026-09-06 13:47 UTCEPSS rescore
  4. 2026-09-05 01:44 UTCOSV refresh
  5. 2026-09-04 05:06 UTCEPSS rescore
  6. 2026-09-02 14:12 UTCEPSS rescore
  7. 2026-09-01 13:53 UTCEPSS rescore
  8. 2026-09-01 04:39 UTCEPSS rescore
  9. 2026-08-30 19:17 UTCEPSS rescore
  10. 2026-08-30 01:22 UTCEPSS rescore
  11. 2026-08-28 21:41 UTCEPSS rescore
  12. 2026-08-27 14:25 UTCEPSS rescore
  13. 2026-08-26 14:46 UTCEPSS rescore
  14. 2026-08-25 13:49 UTCEPSS rescore
  15. 2026-08-23 00:19 UTCEPSS rescore
  16. 2026-08-21 23:49 UTCEPSS rescore
  17. 2026-08-20 22:55 UTCEPSS rescore
  18. 2026-08-19 17:03 UTCEPSS rescore
  19. 2026-08-18 13:48 UTCEPSS rescore
  20. 2026-08-18 12:24 UTCNVD updateCVSS v3 → 9
  21. 2026-08-18 12:21 UTCEG score recompute▲ 0.10
  22. 2026-08-18 12:21 UTCVendor advisory
  23. 2026-08-18 12:14 UTCMITRE cvelistV5CVSS v3 → 9.1
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-16 14:56 UTCEPSS rescore
  26. 2026-08-16 10:47 UTCVendor advisory
  27. 2026-08-16 06:29 UTCEG score recompute
  28. 2026-08-16 06:29 UTCVendor advisory
  29. 2026-08-16 02:14 UTCEPSS rescore
  30. 2026-08-15 01:30 UTCEPSS rescore
  31. 2026-08-14 22:25 UTCVendor advisory
  32. 2026-08-14 18:07 UTCVendor advisory
  33. 2026-08-14 13:13 UTCVendor advisory
  34. 2026-08-14 08:55 UTCVendor advisory
  35. 2026-08-14 04:36 UTCEG score recompute
  36. 2026-08-14 04:36 UTCVendor advisory
  37. 2026-08-13 22:00 UTCEPSS rescore
  38. 2026-08-13 08:51 UTCVendor advisory
  39. 2026-08-13 03:23 UTCVendor advisory
  40. 2026-08-12 23:05 UTCVendor advisory
  41. 2026-08-12 18:47 UTCEG score recompute
  42. 2026-08-12 18:47 UTCVendor advisory
  43. 2026-08-12 13:51 UTCEPSS rescore
  44. 2026-08-12 01:32 UTCVendor advisory
  45. 2026-08-11 21:14 UTCVendor advisory
  46. 2026-08-11 16:57 UTCEG score recompute
  47. 2026-08-11 16:57 UTCVendor advisory
  48. 2026-08-11 13:43 UTCEPSS rescore
  49. 2026-08-11 06:50 UTCVendor advisory
  50. 2026-08-11 02:32 UTCEG score recompute
  51. 2026-08-11 02:32 UTCVendor advisory
  52. 2026-08-11 00:00 UTCEPSS rescore
  53. 2026-08-10 10:15 UTCVendor advisory
  54. 2026-08-10 05:57 UTCVendor advisory
  55. 2026-08-10 01:39 UTCVendor advisory
  56. 2026-08-09 21:20 UTCVendor advisory
  57. 2026-08-09 17:02 UTCEG score recompute
  58. 2026-08-09 17:02 UTCVendor advisory
  59. 2026-08-09 13:46 UTCEPSS rescore
  60. 2026-08-09 12:44 UTCVendor advisory
  61. 2026-08-09 08:10 UTCVendor advisory
  62. 2026-08-09 03:52 UTCEG score recompute
  63. 2026-08-09 03:52 UTCVendor advisory
  64. 2026-08-08 16:37 UTCEPSS rescore
  65. 2026-08-08 11:19 UTCVendor advisory
  66. 2026-08-08 06:31 UTCVendor advisory
  67. 2026-08-08 02:13 UTCVendor advisory
  68. 2026-08-07 21:55 UTCVendor advisory
  69. 2026-08-07 17:37 UTCEG score recompute
  70. 2026-08-07 17:37 UTCVendor advisory
  71. 2026-08-07 13:19 UTCVendor advisory
  72. 2026-08-06 17:28 UTCEG score recompute
  73. 2026-08-06 17:28 UTCVendor advisory
  74. 2026-08-06 13:46 UTCEPSS rescore
  75. 2026-08-06 12:14 UTCVendor advisory

Related CVEs(same product + same vendor + same CWE)

Same product

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Maven:org.thymeleaf:thymeleaf · Maven:org.thymeleaf:thymeleaf-spring5

Frequently asked(5)

What is CVE-2026-40478?
CVE-2026-40478 is a critical vulnerability published on April 17, 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…
When was CVE-2026-40478 disclosed?
CVE-2026-40478 was first published on April 17, 2026, with the most recent update on August 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40478 actively exploited?
CVE-2026-40478 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.2% probability of exploitation in the next 30 days (67th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-40478?
CVE-2026-40478 has a CVSS base score of 9.0 (a secondary CVSS source that NVD displays; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.1 (CRITICAL).
How do I remediate CVE-2026-40478?
A fix for CVE-2026-40478 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-40478 are linked in the Vendor Advisories panel on this page.

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