What is CVE-2021-28156?

CVE-2021-28156 is a high-severity vulnerability in Hashicorp Consul. CVSS score: 7.5/10. Published 2021-04-20.

How severe is CVE-2021-28156?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Hashicorp Consul

CVE-2021-28156

HashiCorp Consul Enterprise version 1.8.0 up to 1.9.4 audit log can be bypassed by specifically crafted HTTP events. Fixed in 1.9.5, and 1.8.10.

Published 2021-04-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.023 (83.0th percentile), scored 2026-10-20.

Low probability of exploitation in the next 30 days, but still tracked. 83rd percentile — 83.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.023 · newest: 0.023 · change: 0.000

Affected products

Hashicorp Consul

References

www.hashicorp.com/blog/category/consul (Vendor Advisory)
discuss.hashicorp.com/t/hcsec-2021-08-consul-enterprise-audit-log-bypass-for-ht… (Vendor Advisory)
security.gentoo.org/glsa/202208-09 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2021-28156?: CVE-2021-28156 is a high-severity vulnerability in Hashicorp Consul. CVSS score: 7.5/10. Published 2021-04-20.
How severe is CVE-2021-28156?: High severity. CVSS v3 base score is 7.5 out of 10.