What’s Vulnerable › Vulnerabilities

CVE-2021-39162: Incorrect handling of H2 GOAWAY + SETTINGS frames

• Severity: medium (CVSS 5.0 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-09-09 · updated 2026-06-17
• Weakness: CWE-754

Description

Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, can abnormally terminate if an H/2 GOAWAY and SETTINGS frame are received in the same IO event. This can lead to a DoS in the presence of untrusted *upstream* servers. 0.15.1 contains an upgraded envoy binary with this vulnerability patched. If only trusted upstreams are configured, there is not substantial risk of this condition being triggered.

Affected products

• envoyproxy envoy: before 1.18.4; 1.19.0 — fixed in 1.18.4
• pomerium: 0.15.0

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.18.4. Check the vendor advisory for mitigations.

References

• https://github.com/envoyproxy/envoy/security/advisories/GHSA-j374-mjrw-vvp8
• https://github.com/pomerium/pomerium/security/advisories/GHSA-gjcg-vrxg-xmgv
• https://groups.google.com/g/envoy-announce/c/5xBpsEZZDfE/m/wD05NZBbAgAJ
• https://github.com/envoyproxy/envoy/security/advisories/GHSA-j374-mjrw-vvp8
• https://github.com/pomerium/pomerium/security/advisories/GHSA-gjcg-vrxg-xmgv
• https://groups.google.com/g/envoy-announce/c/5xBpsEZZDfE/m/wD05NZBbAgAJ

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