CVE-2026-31865 (GCVE-0-2026-31865)
Vulnerability from cvelistv5 – Published: 2026-03-18 02:50 – Updated: 2026-03-18 18:39
VLAI
EPSS
VEX
Title
Elysia Cookie Value Prototype Pollution
Summary
Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. `__proto__`. This issue is patched in 1.4.27. As a workaround, use t.Cookie validation to enforce validation value and/or prevent iterable over cookie if possible.
Severity
6.5 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-18 18:36 UTC
CWE
- CWE-1321 - Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/elysiajs/elysia/security/advis… | x_refsource_CONFIRM |
| https://github.com/elysiajs/elysia/commit/e9d6b17… | x_refsource_MISC |
Impacted products
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},
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"lang": "es",
"value": "Elysia es un framework de Typescript para la validaci\u00f3n de solicitudes, inferencia de tipos, documentaci\u00f3n OpenAPI y comunicaci\u00f3n cliente-servidor. Antes de la versi\u00f3n 1.4.27, una cookie de Elysia pod\u00eda ser sobrescrita mediante contaminaci\u00f3n de prototipos, p. ej. `__proto__`. Este problema est\u00e1 parcheado en la versi\u00f3n 1.4.27. Como soluci\u00f3n alternativa, use la validaci\u00f3n t.Cookie para forzar el valor de validaci\u00f3n y/o evitar la iteraci\u00f3n sobre la cookie si es posible."
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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