CVE-2025-64527
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-03

Last updated on: 2025-12-05

Assigner: GitHub, Inc.

Description
Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, Envoy crashes when JWT authentication is configured with the remote JWKS fetching, allow_missing_or_failed is enabled, multiple JWT tokens are present in the request headers and the JWKS fetch fails. This is caused by a re-entry bug in the JwksFetcherImpl. When the first token's JWKS fetch fails, onJwksError() callback triggers processing of the second token, which calls fetch() again on the same fetcher object. The original callback's reset() then clears the second fetch's state (receiver_ and request_) which causes a crash when the async HTTP response arrives.
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Meta Information
Published
2025-12-03
Last Modified
2025-12-05
Generated
2026-06-16
AI Q&A
2025-12-03
EPSS Evaluated
2026-06-15
NVD
CVE-2025-64527
EUVD
EUVD-2025-201100
Affected Vendors & Products
Showing 4 associated CPEs
Vendor Product Version / Range
envoyproxy envoy to 1.33.13 (exc)
envoyproxy envoy From 1.34.0 (inc) to 1.34.11 (exc)
envoyproxy envoy From 1.35.0 (inc) to 1.35.7 (exc)
envoyproxy envoy From 1.36.0 (inc) to 1.36.3 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-476 The product dereferences a pointer that it expects to be valid but is NULL.
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Executive Summary

This vulnerability occurs in Envoy proxy versions 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier when JWT authentication is configured with remote JWKS fetching and the allow_missing_or_failed option is enabled. If multiple JWT tokens are present in the request headers and the JWKS fetch fails, a re-entry bug in the JwksFetcherImpl causes Envoy to crash. Specifically, when the first token's JWKS fetch fails, the onJwksError() callback triggers processing of the second token, which calls fetch() again on the same fetcher object. The original callback's reset() then clears the second fetch's state, leading to a crash when the asynchronous HTTP response arrives.

Impact Analysis

This vulnerability can cause the Envoy proxy to crash when processing requests with multiple JWT tokens under certain conditions. This crash results in a denial of service (DoS) condition, potentially disrupting the availability of services relying on Envoy for authentication and proxying.

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