CVE-2021-45079Network attack vector

Authentication bypass via early EAP-Success

Published Jan 31, 2022 · Updated Aug 4, 2024

Authentication bypass in strongSwan before 5.9.5 allows remote attackers to bypass client authentication via early EAP-Success messages. The EAP client unconditionally calls get_msk() when an EAP-Success arrives before a method has completed, causing an IKE daemon crash or premature authentication completion. Exploitation requires EAP authentication; with EAP-only mutual methods, a rogue responder can also bypass server authentication and read unencrypted tunnel traffic or reach client-selected subnets.

CVSS severity5.8
Medium
EPSS probability2.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in strongSwan before 5.9.5 allows remote attackers to bypass client authentication via early EAP-Success messages. The EAP client unconditionally calls get_msk() when an EAP-Success arrives before a method has completed, causing an IKE daemon crash or premature authentication completion. Exploitation requires EAP authentication; with EAP-only mutual methods, a rogue responder can also bypass server authentication and read unencrypted tunnel traffic or reach client-selected subnets.

The record

CVE
CVE-2021-45079
Published
Jan 31, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 31, 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?

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

5.8NVDAV:N/AC:M/Au:N/C:P/I:N/A:P
9.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

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-476NULL Pointer Dereference
T1557Adversary-in-the-Middle

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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