TI-2026-35881 Aliases CVE-2026-48521

NULL pointer dereference in envoyproxy envoy

MEDIUM 60CWE-476Published 2026-09-21 · Updated 2026-09-21

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-476.

Summary

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's ProdClusterManagerFactory::allocateConnPool dereferences transport_socket_options while selecting an HTTP/3 connection pool without first checking whether the pointer is null. LoadBalancerContext implementations used by synthetic, mirror, health-check, and async-client calls can return no transport-socket options. With auto_config and HTTP/3 enabled, routine traffic reaching one of those contexts can crash an Envoy worker. The relevant scope boundary is that the affected branch requires HTTP/3 in the protocol set and a context that supplies no transport-socket options. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00739 54th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed envoy (envoyproxy): 1.36.10, 1.37.6, 1.38.4 +1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
envoyproxy	envoy	before 1.36.10; 1.37.0 to before 1.37.6; 1.38.0 to before 1.38.4; 1.39.0 to before 1.39.1	1.36.10, 1.37.6, 1.38.4, 1.39.1	Patch available	CNA

envoy Vendorenvoyproxy Affected before 1.36.10; 1.37.0 to before 1.37.6; 1.38.0 to before 1.38.4; 1.39.0 to before 1.39.1 Fixed in 1.36.10, 1.37.6, 1.38.4, 1.39.1 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:envoyproxy:envoy::::::::	before 1.36.10; 1.37.0 to before 1.37.6; 1.38.0 to before 1.38.4; 1.39.0 to before 1.39.1	Vulnerable	envoyproxy

cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* Versions before 1.36.10; 1.37.0 to before 1.37.6; 1.38.0 to before 1.38.4; 1.39.0 to before 1.39.1 Vulnerable ·envoyproxy

Remediation

Fix · CNA envoy (envoyproxy) Fixed in 1.36.10, 1.37.6, 1.38.4, 1.39.1

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 1 product

OpenShift Service Mesh 3

Timeline

2026-10-02 Threatist record created from CVE-2026-48521

References

Exploit 1

https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3

Patch 4

Other 4

TI-2026-79288 Out-of-bounds write in Google Brotli decoder KEVCVSS 4.0CRITICAL 9.2
TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
TI-2024-20001 HTTP/2: CPU exhaustion due to CONTINUATION frame flood CVSS 3.1HIGH 7.5
TI-2024-18524 HTTP/2: memory exhaustion due to CONTINUATION frame flood CVSS 3.1HIGH 7.5
TI-2023-12215 Envoy client may fake the header `x-envoy-original-path` CVSS 3.1CRITICAL 9.1
TI-2023-18002 Envoy vulnerable to OAuth2 credentials exploit with permanent validity CVSS 3.1CRITICAL 9.8

See all 126 →

Sources

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