Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation and client-server communication. Versions 1.4.17 and below are subject to arbitrary code execution from cookie config. When dynamic cookies are enabled (e.g. there an existing cookie schema), the cookie config is injected into the compiled route without first being sanitised. Availability of this exploit is generally low, but when combined with GHSA-hxj9-33pp-j2cc, it allows for a full RCE chain. An attack requires write access to either the Elysia app's source code (in which case the vulnerability is meaningless) or write access to the cookie config (perhaps where it is assumed to be provisioned by the environment). This issue is fixed in version 1.4.18.
CVE-2025-66457
This high-severity CVE scores 8.8 under NVD CVSS v3. EPSS exploit probability: 0.7%, top 50% 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).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.8
- EG Score
- 8.8(medium)
- EG Risk
- 56(Track*)EG Risk 56/100SSVC: 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 computedSeverity88% × 45%Exploitation40% × 40%Automatability0% × 15%Action: Watch closely — could escalate to Attend. - EPSS
- 49.5%
- KEV
- Not listed
Published
December 9, 2025
Last Modified
June 17, 2026
References (6)
- security-advisories@githubhttps://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e
- security-advisories@githubhttps://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849e
- security-advisories@githubhttps://github.com/elysiajs/elysia/pull/1564
- security-advisories@githubhttps://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf
- security-advisories@githubhttps://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc
- 134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/sportshead/elysia-poc
Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| elysia | — | 1.4.18 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 13× in last 7d / 48× 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.
- 2026-07-23 14:18 UTCEPSS rescore
- 2026-07-23 14:18 UTCEPSS rescore
- 2026-07-23 13:19 UTCOSV refresh
- 2026-07-23 03:01 UTCEG score recompute
- 2026-07-22 14:08 UTCEPSS rescore
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- 2026-07-07 13:46 UTCEPSS rescore
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- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 08:11 UTCOSV refresh
- 2026-07-06 02:23 UTCEPSS rescore
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- 2026-06-19 19:25 UTCEPSS rescore
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- 2026-06-18 17:52 UTCEPSS rescore
- 2026-06-18 17:52 UTCEPSS rescore
- 2026-06-17 20:05 UTCOSV refresh
- 2026-06-17 17:52 UTCEPSS rescore
- 2026-06-16 17:52 UTCEPSS rescore
- 2026-06-15 17:48 UTCEPSS rescore
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- 2026-06-14 23:18 UTCEPSS rescore
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- 2026-06-10 13:22 UTCEPSS rescore
- 2026-06-08 14:17 UTCEPSS rescore
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- 2026-06-07 15:24 UTCEPSS rescore
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- 2026-06-06 13:47 UTCEPSS rescore
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- 2026-06-05 22:46 UTCEPSS rescore
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- 2026-06-05 06:10 UTCEPSS rescore
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- 2026-06-04 13:12 UTCEPSS rescore
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- 2026-06-02 20:13 UTCEPSS rescore
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- 2026-06-01 13:51 UTCEPSS rescore
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- 2026-05-31 00:16 UTCEPSS rescore
- 2026-05-31 00:16 UTCEPSS rescore
- 2026-05-29 18:02 UTCEG score recompute
- 2026-05-29 13:44 UTCEPSS rescore
Related CVEs(same CWE)
Same CWE
10 shownCWE-94
Frequently asked(5)
What is CVE-2025-66457?
When was CVE-2025-66457 disclosed?
Is CVE-2025-66457 actively exploited?
What is the CVSS score of CVE-2025-66457?
How do I remediate CVE-2025-66457?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-66457
Is Your Infrastructure Affected by CVE-2025-66457?
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