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%CVSS: 9.0Exploit: None knownExposed: 0

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
9.1(medium)
EG Risk
41(Track)
EG Risk 41/100SSVC: Track

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%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
56%
KEV
Not listed

Published

April 17, 2026

Last Modified

August 18, 2026

Advisory Details (1)

Auto-updated May 2, 2026
Patch available. Sources: github.
github Patch Available

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 / EcosystemFixed in / 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 rangeFixed inDependents
org.thymeleaf:thymeleaf1.0.0 ... m1 (81 versions)3.1.4.RELEASE—
org.thymeleaf:thymeleaf-spring53.0.10.RELEASE ... 3.1.3.RELEASE (22 versions)3.1.4.RELEASE—
org.thymeleaf:thymeleaf-spring63.1.0.M1 ... 3.1.3.RELEASE (9 versions)3.1.4.RELEASE—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 90× 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 226 total refreshes for this CVE.

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

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 in the National Vulnerability Database 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% probability of exploitation in the next 30 days, which ranks it in the top 44.1% of all scored CVEs.
What is the CVSS score of CVE-2026-40478?
CVE-2026-40478 has a CVSS v3 base score of 9.0 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.1.
How do I remediate CVE-2026-40478?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40478, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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