CVE-2026-26311Public exploitNetwork attack vector

Unauthenticated proxy crash via reset-stream filter callbacks

Published Mar 10, 2026 · Updated Mar 10, 2026

Use-after-free in Envoy before 1.34.13, 1.35.0 through 1.35.8, 1.36.0 through 1.36.4, and 1.37.0 allows remote attackers to crash the proxy. FilterManager::decodeData omits the saw_downstream_reset_ check and calls decodeData on decoder filters after onDestroy has run. An unauthenticated HTTP/2 or HTTP/3 peer must deliver DATA during the deferred-deletion window; successful exploitation terminates the Envoy process.

CVSS severity5.9
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use-after-free in Envoy before 1.34.13, 1.35.0 through 1.35.8, 1.36.0 through 1.36.4, and 1.37.0 allows remote attackers to crash the proxy. FilterManager::decodeData omits the saw_downstream_reset_ check and calls decodeData on decoder filters after onDestroy has run. An unauthenticated HTTP/2 or HTTP/3 peer must deliver DATA during the deferred-deletion window; successful exploitation terminates the Envoy process.

The record

CVE
CVE-2026-26311
Published
Mar 10, 2026
Updated
Mar 10, 2026
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 10, 2026Record 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=< 1.34.13
  2. Affected versionversion=>= 1.35.0, < 1.35.9
  3. Affected versionversion=>= 1.36.0, < 1.36.5
  4. Affected versionversion=>= 1.37.0, < 1.37.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=< 1.34.13; version=>= 1.35.0, < 1.35.9; version=>= 1.36.0, < 1.36.5; version=>= 1.37.0, < 1.37.1

Published CVSS scores

5.9GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo