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Fencer Vulns
high 8.6

CVE-2023-35941 json

Envoy vulnerable to OAuth2 credentials exploit with permanent validity

published 2023-07-25 3 y ago modified 2026-09-08 2 mo ago also BIT-envoy-2023-35941 , EUVD-2023-39925 , GHSA-7mhv-gr67-hq55

cvss
8.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

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.

Patch / fix

  • bitnami envoy 1.23.12, 1.24.10, 1.25.9, 1.26.4
  • envoyproxy envoy 1.23.12, 1.24.10, 1.25.9, 1.26.4

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-35941 updated cvss 8.6

envoy: OAuth2 credentials exploit with permanent validity

  • Red Hat RHOSSM 2.2 for RHEL 8 openshift-service-mesh/proxyv2-rhel8 2.2.10-3
    fixed: vendor fix RHSA-2023:5175
  • Red Hat RHOSSM 2.3 for RHEL 8 openshift-service-mesh/proxyv2-rhel8 2.3.6-4
    fixed: vendor fix RHSA-2023:4624
  • Red Hat RHOSSM 2.4 for RHEL 8 openshift-service-mesh/proxyv2-rhel8 2.4.2-7
    fixed: vendor fix RHSA-2023:4625
  • Red Hat RHOSSM 2.2 for RHEL 8 openshift-service-mesh/kiali-rhel8 1.48.8-1, openshift-service-mesh/pilot-rhel8 2.2.10-2, openshift-service-mesh/grafana-rhel8 2.2.10-1, openshift-service-mesh/istio-cni-rhel8 2.2.10-2, openshift-service-mesh/ratelimit-rhel8 2.2.10-1, openshift-service-mesh/prometheus-rhel8 2.2.10-1, +1 more Red Hat RHOSSM 2.3 for RHEL 8 openshift-service-mesh/pilot-rhel8 2.3.6-2, openshift-service-mesh/grafana-rhel8 2.3.6-1, openshift-service-mesh/istio-cni-rhel8 2.3.6-2, openshift-service-mesh/ratelimit-rhel8 2.3.6-1, openshift-service-mesh/prometheus-rhel8 2.3.6-1, openshift-service-mesh/istio-must-gather-rhel8 2.3.6-2 Red Hat RHOSSM 2.4 for RHEL 8 openshift-service-mesh/pilot-rhel8 2.4.2-8, openshift-service-mesh/grafana-rhel8 2.4.2-3, openshift-service-mesh/istio-cni-rhel8 2.4.2-8, openshift-service-mesh/ratelimit-rhel8 2.4.2-4, openshift-service-mesh/istio-rhel8-operator 2.4.2-8, openshift-service-mesh/istio-must-gather-rhel8 2.4.2-4
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
bitnami envoy
>=1.23.0, <1.23.12
>=1.24.0, <1.24.10
>=1.25.0, <1.25.9
>=1.26.0, <1.26.4
1.23.12
1.24.10
1.25.9
1.26.4

Affected products

  • envoyproxy envoy

Classification

Weakness
  • CWE-116 Improper Encoding or Escaping of Output

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.