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TI-2023-18002 Aliases CVE-2023-35941

Envoy vulnerable to OAuth2 credentials exploit with permanent validity

Priority HIGH 75CWE-116Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

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

Summary

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, a malicious client is able to construct credentials with permanent validity in some specific scenarios. This is caused by the some rare scenarios in which HMAC payload can be always valid in OAuth2 filter's check. Versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12 have a fix for this issue. As a workaround, avoid wildcards/prefix domain wildcards in the host's domain configuration.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00814 57th percentileScored 2026-11-07
Fix Fixed envoy (envoyproxy): 1.26.4, 1.25.9, 1.24.10 +1Red Hat: 3 advisories

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

VendorProductAffected versionsFixed inStatusSource
envoyproxyenvoy1.26.0 to before 1.26.4; 1.25.0 to before 1.25.9; 1.24.0 to before 1.24.10; before 1.23.121.26.4, 1.25.9, 1.24.10, 1.23.12Patch availableCNA
  • envoy Vendorenvoyproxy Affected 1.26.0 to before 1.26.4; 1.25.0 to before 1.25.9; 1.24.0 to before 1.24.10; before 1.23.12 Fixed in 1.26.4, 1.25.9, 1.24.10, 1.23.12 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*1.23.0 to before 1.23.12; 1.24.0 to before 1.24.10; 1.25.0 to before 1.25.9; 1.26.0 to before 1.26.4Vulnerableenvoyproxy
  • cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* Versions 1.23.0 to before 1.23.12; 1.24.0 to before 1.24.10; 1.25.0 to before 1.25.9; 1.26.0 to before 1.26.4 Vulnerable ·envoyproxy

Remediation

  • Fix · CNA envoy (envoyproxy) Fixed in 1.26.4, 1.25.9, 1.24.10, 1.23.12

Red Hat 3 advisories

  • RHSA-2023:5175 Released 2023-09-14 · Red Hat rating Important
    Red Hat OpenShift Service Mesh 2.2.10 security update
    • RHOSSM 2.2 for RHEL 8 openshift-service-mesh/proxyv2-rhel8
  • RHSA-2023:4625 Released 2023-08-11 · Red Hat rating Important
    Red Hat OpenShift Service Mesh Containers for 2.4.2 security update
    • RHOSSM 2.4 for RHEL 8 openshift-service-mesh/proxyv2-rhel8
  • RHSA-2023:4624 Released 2023-08-11 · Red Hat rating Important
    Red Hat OpenShift Service Mesh Containers for 2.3.6 security update
    • RHOSSM 2.3 for RHEL 8 openshift-service-mesh/proxyv2-rhel8

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
RHOSSM 2.2 for RHEL 8Fixed RHSA-2023:5175
RHOSSM 2.3 for RHEL 8Fixed RHSA-2023:4624
RHOSSM 2.4 for RHEL 8Fixed RHSA-2023:4625
Not affected: 3 products
  • RHOSSM 2.2 for RHEL 8
  • RHOSSM 2.3 for RHEL 8
  • RHOSSM 2.4 for RHEL 8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2023-35941

References

Advisory 1

  • 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-2023-12221 Envoy doesn't escape HTTP header values CVSS 3.1CRITICAL 9.1
See all 126 →

Sources

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