CVE-2021-43999Network attack vector

Account impersonation via insufficient SAML response validation

Published Jan 11, 2022 · Updated Aug 4, 2024

Improper authentication in Apache Guacamole 1.2.0 and 1.3.0 allows remote authenticated users to assume another user's identity through SAML. Guacamole accepts an insufficiently validated response from the configured SAML identity provider, but Apache has not disclosed the missing validation step or affected code locus. When SAML support is enabled, a malicious user can inherit the permissions and remote-desktop access assigned to the impersonated Guacamole account.

CVSS severity8.8
High
EPSS probability1.78%
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 Apache Guacamole 1.2.0 and 1.3.0 allows remote authenticated users to assume another user's identity through SAML. Guacamole accepts an insufficiently validated response from the configured SAML identity provider, but Apache has not disclosed the missing validation step or affected code locus. When SAML support is enabled, a malicious user can inherit the permissions and remote-desktop access assigned to the impersonated Guacamole account.

The record

CVE
CVE-2021-43999
Published
Jan 11, 2022
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Guacamole
Classifications
CWE-287, T1078
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 11, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=1.2.0
  2. Affected versionversion=1.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Apache Software Foundation · Apache Guacamoleversion=1.2.0; version=1.3.0

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.0NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1078Valid Accounts

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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