Envoy: HTTP - filter chain execution on reset streams causing UAF crash

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-26311: 0.36% estimated exploitation activity in the next 30 days; percentile 29.60 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Note: This vulnerability was originally reported to the Google OSS VRP (Issue ID: 477542544). The Google Security Team requested that I coordinate directly with the Envoy maintainers for triage and remediation. I am submitting this report here to facilitate that process. Technical Details I have identified a logic vulnerability in Envoy's HTTP connection manager (FilterManager) that allows for Zombie Stream Filter Execution. This issue creates a "Use-After-Free" (UAF) or state-corruption window where filter callbacks are invoked on an HTTP stream that has already been logically reset and cleaned up. Mechanism: The vulnerability resides in source/common/http/filtermanager.cc within the FilterManager::decodeData method. When an HTTP/2 stream encounters a reset condition (e.g., StreamIdleTimeout, OverloadManager limits, or a local reset triggered by a filter), Envoy calls onResetStream. This method: 1. Sets the internal state state.sawdownstreamreset = true. 2. Invokes onDestroy() on…

Published by the source

10 Mar 2026, 18:31 UTC

Last modified by the source

10 Mar 2026, 22:54 UTC

Source last checked

26 Oct 2026, 15:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-84xm-r438-86px

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# Patch Next advisory brief: CVE-2026-26311

Advisory: Envoy: HTTP - filter chain execution on reset streams causing UAF crash
IDs: CVE-2026-26311, GHSA-84xm-r438-86px
Record: https://patchnext.com/advisories/cve-2026-26311 (revision 1, source checked 26 Oct 2026, 15:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/envoyproxy/envoy: affected >= 1.37.0, <= 1.37.0; >= 1.36.0, <= 1.36.4; >= 1.35.0, <= 1.35.8; <= 1.34.12

## Suggested inspection (read-only)
- Go github.com/envoyproxy/envoy: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/envoyproxy/envoy.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-84xm-r438-86px (GitHub-reviewed advisory GHSA-84xm-r438-86px lists affected ranges: Go github.com/envoyproxy/envoy >=1.37.0 =1.36.0 =1.35.0 =0 <=1.34.12)

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