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Envoy CVE-2025-64527

| EUVDEUVD-2025-201100 MEDIUM
NULL Pointer Dereference (CWE-476)
2025-12-03 security-advisories@github.com GHSA-mp85-7mrq-r866
6.5
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
6.5 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat
6.5 MEDIUM
qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
EUVD ID Assigned
Mar 15, 2026 - 16:14 euvd
EUVD-2025-201100
Analysis Generated
Mar 15, 2026 - 16:14 vuln.today
PoC Detected
Dec 05, 2025 - 16:56 vuln.today
Public exploit code
CVE Published
Dec 03, 2025 - 18:15 nvd
MEDIUM 6.5

DescriptionGitHub Advisory

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.

Analysis

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.

Technical ContextAI

A NULL pointer dereference occurs when the application attempts to use a pointer that has not been initialized or has been set to NULL.

RemediationAI

Add NULL checks before pointer dereference operations. Use static analysis to identify potential NULL pointer issues. Enable compiler warnings.

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Vendor StatusVendor

Debian

Bug #987544
envoyproxy
Release Status Fixed Version Urgency
open - -

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CVE-2025-64527 vulnerability details – vuln.today

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