CVE-2021-28156Network attack vector

Audit-log bypass via crafted HTTP parameters

Published Apr 20, 2021 · Updated Aug 3, 2024

Audit-log bypass in HashiCorp Consul Enterprise 1.8.0 through 1.9.4 allows remote attackers to suppress valid HTTP events. Requests containing specific crafted parameters remain valid for processing, but the audit subsystem incorrectly excludes their HTTP events instead of recording them. The Enterprise-only audit feature covers HTTP API activity, and exploitation removes accountability for attempted or committed operations.

CVSS severity7.5
High
EPSS probability2.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Audit-log bypass in HashiCorp Consul Enterprise 1.8.0 through 1.9.4 allows remote attackers to suppress valid HTTP events. Requests containing specific crafted parameters remain valid for processing, but the audit subsystem incorrectly excludes their HTTP events instead of recording them. The Enterprise-only audit feature covers HTTP API activity, and exploitation removes accountability for attempted or committed operations.

The record

CVE
CVE-2021-28156
Published
Apr 20, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1562
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NVDAV:N/AC:L/Au:N/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1562Impair Defenses

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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