CVE-2021-1725Network attack vector

Information disclosure via crafted claim authentication

Published Jan 12, 2021 · Updated Oct 8, 2024

Improper authentication in Microsoft Bot Framework SDK allows attackers with bot knowledge to submit accepted malicious skill claims. The claims-authentication path accepts crafted skill claims when the host bot lacks a ClaimsValidator that rejects skill callers. Exposure requires internal knowledge of the bot and a bot not configured as a Skill; accepted claims can expose information handled by the bot.

CVSS severity5.5
Medium
EPSS probability1.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in Microsoft Bot Framework SDK allows attackers with bot knowledge to submit accepted malicious skill claims. The claims-authentication path accepts crafted skill claims when the host bot lacks a ClaimsValidator that rejects skill callers. Exposure requires internal knowledge of the bot and a bot not configured as a Skill; accepted claims can expose information handled by the bot.

The record

CVE
CVE-2021-1725
Published
Jan 12, 2021
Updated
Oct 8, 2024
Vendor
Microsoft
Product
Microsoft Bot Framework SDK for JavaScript
Classifications
CWE-287
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 8, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.0.0 <publication

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Bot Framework SDK for JavaScriptversion=4.0.0 <publication
Microsoft · Microsoft Bot Framework SDK for .NET Frameworkversion=4.0.0 <publication
Microsoft · Microsoft Bot Framework SDK for Pythonversion=4.0.0 <publication

Published CVSS scores

2.1NIST National Vulnerability DatabaseAV:L/AC:L/Au:N/C:P/I:N/A:N
5.5Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

CWE-287Improper Authentication

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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