CVE-2025-62504Network attack vector

Service crash via dangling response-header references

Published Oct 16, 2025 · Updated Oct 17, 2025

Use-after-free in the Lua HTTP filter in Envoy allows remote authenticated users to crash the proxy via responses rewritten by Lua scripts. An oversized rewritten body triggers a local reply whose replacement headers invalidate references to the original response headers. Reachability requires a response-phase Lua script to exceed the configured buffer limit; exploitation terminates Envoy and interrupts proxied traffic.

CVSS severity6.5
Medium
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Lua HTTP filter in Envoy allows remote authenticated users to crash the proxy via responses rewritten by Lua scripts. An oversized rewritten body triggers a local reply whose replacement headers invalidate references to the original response headers. Reachability requires a response-phase Lua script to exceed the configured buffer limit; exploitation terminates Envoy and interrupts proxied traffic.

The record

CVE
CVE-2025-62504
Published
Oct 16, 2025
Updated
Oct 17, 2025
Vendor
Envoy Proxy
Product
Envoy
Classifications
T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 17, 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.

  1. Affected versionversion=<= 1.33.11
  2. Affected versionversion=>= 1.34.0, <= 1.34.9
  3. Affected versionversion=>= 1.350, <= 1.35.5
  4. Affected versionversion=>= 1.36.0, <= 1.36.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Envoy Proxy · Envoyversion=<= 1.33.11; version=>= 1.34.0, <= 1.34.9; version=>= 1.350, <= 1.35.5; version=>= 1.36.0, <= 1.36.1

Published CVSS scores

6.5Envoy Proxy GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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