CVE-2021-1677

Pod identity spoofing via ARP poisoning

Published Jan 12, 2021 · Updated Nov 19, 2024

Spoofing in Azure Active Directory pod identity for Microsoft Azure Kubernetes Service before publication allows local users to steal managed-identity tokens via ARP poisoning. The pod networking bridge accepts ARP and IP spoofed traffic, allowing a compromised pod to impersonate another pod when contacting the Azure Instance Metadata Service. An attacker already executing code in a pod must share the cluster network; successful spoofing discloses other pods' Azure identity credentials without altering data or interrupting service.

CVSS severity5.5
Medium
EPSS probability1.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Spoofing in Azure Active Directory pod identity for Microsoft Azure Kubernetes Service before publication allows local users to steal managed-identity tokens via ARP poisoning. The pod networking bridge accepts ARP and IP spoofed traffic, allowing a compromised pod to impersonate another pod when contacting the Azure Instance Metadata Service. An attacker already executing code in a pod must share the cluster network; successful spoofing discloses other pods' Azure identity credentials without altering data or interrupting service.

The record

CVE
CVE-2021-1677
Published
Jan 12, 2021
Updated
Nov 19, 2024
Vendor
Microsoft
Product
Azure Kubernetes Service
Classifications
CWE-290, T1557
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 19, 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?

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  1. Affected versionversion=2022.0.0 <publication

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Azure Kubernetes Serviceversion=2022.0.0 <publication

Published CVSS scores

5.5MicrosoftCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
2.1NVDAV:L/AC:L/Au:N/C:P/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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