CVE-2021-39204
Excessive CPU usage in Pomerium
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Excessive CPU usage in Pomerium
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
- Record
CVE-2021-39204- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-834
- Updated
- 2026-11-02
EUVDEUVD-2021-1989
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
- Record
EUVD-2021-1989- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-5wjf-62hw-q78r
Excessive CPU usage
Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset.
Impact
This can result in a DoS condition.
Patches
Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
Workarounds
N/A
References
envoy GSA envoy CVE envoy announcement
For more information
If you have any questions or comments about this advisory:
- Open an issue in pomerium/pomerium
- Email us at [email protected]
- Record
GHSA-5wjf-62hw-q78r- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-834
- Updated
- 2026-11-02
NVD
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
- Record
CVE-2021-39204- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-834
- Updated
- 2026-11-02
OSV
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
- Record
CVE-2021-39204- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVGHSA-5wjf-62hw-q78r
Excessive CPU usage
Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset.
Impact
This can result in a DoS condition.
Patches
Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
Workarounds
N/A
References
envoy GSA envoy CVE envoy announcement
For more information
If you have any questions or comments about this advisory:
- Open an issue in pomerium/pomerium
- Email us at [email protected]
- Record
GHSA-5wjf-62hw-q78r- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-834
- Updated
- 2026-11-02
OSVBIT-envoy-2021-39204 No score
Excessive CPU usage in Pomerium
Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.
- Record
BIT-envoy-2021-39204- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
github.com/pomerium/pomeriumGo |
before 0.14.8 | 0.14.8 |
github.com/pomerium/pomeriumGo |
0.15.0 to 0.15.0 | 0.15.1 |
envoyBitnami |
before 1.16.5, 1.17.0 up to 1.17.4, 1.18.0 up to 1.18.4, 1.19.0 up to 1.19.1 | 1.16.51.17.41.18.41.19.1 |
github.com/pomerium/pomeriumGo |
0.15.0 up to 0.15.1 | 0.15.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-39204 is a high vulnerability (CVSS 7.5) in Envoyproxy Envoy, published September 9, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.66%, the 76th percentile. Fixed in github.com/pomerium/pomerium 0.14.8.
References
groups.google.com/g/envoy-announce/c/5xBpsEZZDfE/m/wD05NZBbAgAJ
github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc
nvd.nist.gov/vuln/detail/CVE-2021-39204