TI-2024-15428 Aliases CVE-2024-23326

Envoy incorrectly accepts HTTP 200 response for entering upgrade mode

LOW 36CWE-391Published 2024-06-04 · Updated 2024-08-01

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: High · Low · None
Fix status: Partial Red Hat: 1 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

Envoy is a cloud-native, open source edge and service proxy. A theoretical request smuggling vulnerability exists through Envoy if a server can be tricked into adding an upgrade header into a response. Per RFC https://www.rfc-editor.org/rfc/rfc7230#section-6.7 a server sends 101 when switching protocols. Envoy incorrectly accepts a 200 response from a server when requesting a protocol upgrade, but 200 does not indicate protocol switch. This opens up the possibility of request smuggling through Envoy if the server can be tricked into adding the upgrade header to the response.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00361 30th percentileScored 2026-11-07

Fix Partial Red Hat: 1 advisoryRed Hat: 1 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
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	1.13.0 – 1.30.1; 1.29.0 – 1.29.4; 1.28.0 – 1.28.3; up to 1.27.5	—	No fix listed	CNA

envoy Vendorenvoyproxy Affected 1.13.0 – 1.30.1; 1.29.0 – 1.29.4; 1.28.0 – 1.28.3; up to 1.27.5 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:envoyproxy:envoy::::::::	before 1.27.6; 1.28.0 to before 1.28.4; 1.29.0 to before 1.29.5; 1.30.0 to before 1.30.2	Vulnerable	envoyproxy

cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* Versions before 1.27.6; 1.28.0 to before 1.28.4; 1.29.0 to before 1.29.5; 1.30.0 to before 1.30.2 Vulnerable ·envoyproxy

Remediation

Red Hat 1 advisory

RHSA-2024:7725 Released 2024-10-07 · Red Hat rating Important
Red Hat OpenShift Service Mesh Containers for 2.5.5
- RHOSSM 2.5 for RHEL 8 openshift-service-mesh/grafana-rhel8, openshift-service-mesh/istio-cni-rhel8, openshift-service-mesh/istio-must-gather-rhel8 +5

Vendor assessments

Red Hat

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

Product	Status	Plan or fix
OpenShift Service Mesh 2	Affected	No fix planned: Will not fix
RHOSSM 2.5 for RHEL 8	Fixed	RHSA-2024:7725

Timeline

2026-10-02 Threatist record created from CVE-2024-23326

References

Advisory 1

https://github.com/envoyproxy/envoy/security/advisories/GHSA-vcf8-7238-v74c

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

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences