Service crash via JWKS fetcher state reset
Published Dec 3, 2025 · Updated Dec 3, 2025
NULL pointer dereference in affected Envoy releases through 1.36.2 allows remote authenticated users to crash the proxy via crafted JWT headers. The JwksFetcherImpl error callback re-enters fetch() for a second token, then reset() clears receiver_ and request_ for that in-flight fetch, causing the asynchronous response to dereference cleared state. Exploitation requires remote JWKS fetching, allow_missing_or_failed or allow_missing, two Authorization headers, and a failed JWKS fetch; the consequence is an Envoy process crash.
Summary
What happened
NULL pointer dereference in affected Envoy releases through 1.36.2 allows remote authenticated users to crash the proxy via crafted JWT headers. The JwksFetcherImpl error callback re-enters fetch() for a second token, then reset() clears receiver_ and request_ for that in-flight fetch, causing the asynchronous response to dereference cleared state. Exploitation requires remote JWKS fetching, allow_missing_or_failed or allow_missing, two Authorization headers, and a failed JWKS fetch; the consequence is an Envoy process crash.
The record
- CVE
- CVE-2025-64527
- Published
- Dec 3, 2025
- Updated
- Dec 3, 2025
- Vendor
- Envoy Proxy
- Product
- Envoy
- Classifications
- CWE-476, T1499.004
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 3, 2025CVE publishedPublication date reported by the CVE source.
- Dec 3, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=<= 1.33.12
- Affected versionversion=>= 1.34.0, <= 1.34.10
- Affected versionversion=>= 1.35.0, <= 1.35.6
- Affected versionversion=>= 1.36.0, <= 1.36.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream remote-JWKS crash proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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