CVE-2025-62409Public exploitNetwork attack vector

Proxy crash via null buffer-watermark callback

Published Oct 16, 2025 · Updated Oct 16, 2025

NULL pointer dereference in Envoy allows remote attackers to crash the proxy by sending large requests or responses and closing early. While a TCP connection is closing, continuing upstream data invokes a buffer-watermark callback through a null pointer in connection-pool flow control. TCP proxy and mixed HTTP/1 or HTTP/2 ALPN paths are exposed; successful exploitation terminates the Envoy process and interrupts proxied traffic.

CVSS severity7.5
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Envoy allows remote attackers to crash the proxy by sending large requests or responses and closing early. While a TCP connection is closing, continuing upstream data invokes a buffer-watermark callback through a null pointer in connection-pool flow control. TCP proxy and mixed HTTP/1 or HTTP/2 ALPN paths are exposed; successful exploitation terminates the Envoy process and interrupts proxied traffic.

The record

CVE
CVE-2025-62409
Published
Oct 16, 2025
Updated
Oct 16, 2025
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 16, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.33.10
  2. Affected versionversion=>= 1.34.0, < 1.34.9
  3. Affected versionversion=>= 1.35.0, < 1.35.5
  4. Affected versionversion=>= 1.36.0, < 1.36.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=< 1.33.10; version=>= 1.34.0, < 1.34.9; version=>= 1.35.0, < 1.35.5; version=>= 1.36.0, < 1.36.1

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.6GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

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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