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Fencer Vulns
critical 9.1

CVE-2021-45079 json

In strongSwan before 5.9.5, a malicious responder can send an EAP-Success message too early without actually authenticating the client and…

published 2022-01-31 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-31872

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.8%
EPSS 2.8% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

In strongSwan before 5.9.5, a malicious responder can send an EAP-Success message too early without actually authenticating the client and (in the case of EAP methods with mutual authentication and EAP-only authentication for IKEv2) even without server authentication.

Patch / fix

  • strongswan strongswan 5.9.5
  • strongswan Debian 14, Debian 13, Debian 12 5.9.5-1

debian advisories DEBIAN-CVE-2021-45079

  • strongswan Ubuntu 18.04 LTS 5.6.2-1ubuntu2.8
  • strongswan Ubuntu 20.04 LTS 5.8.2-1ubuntu3.4
  • strongswan Ubuntu 22.04 LTS 5.9.4-1ubuntu4
  • strongswan Ubuntu Pro 14.04 LTS 5.1.2-0ubuntu2.11+esm2
  • strongswan Ubuntu Pro 16.04 LTS 5.3.5-1ubuntu3.8+esm2
  • strongswan Ubuntu Pro FIPS-updates 16.04 LTS 5.3.5-1ubuntu3.fips.3.8.3
  • strongswan Ubuntu Pro FIPS-updates 18.04 LTS 5.6.2-1ubuntu2.fips.2.8.1
  • strongswan Ubuntu Pro FIPS-updates 20.04 LTS 5.8.2-1ubuntu3.fips.3.4.1

ubuntu advisories UBUNTU-CVE-2021-45079

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • strongswan SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 4.4.0-6.36.12.1
  • strongswan SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +10 more 5.8.2-11.24.1
  • strongswan SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +7 more 5.8.2-4.17.1
  • strongswan SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +10 more 5.1.3-26.20.1

suse advisories SUSE-SU-2022:14887-1SUSE-SU-2022:0492-1SUSE-SU-2022:0211-1SUSE-SU-2022:0202-1

  • strongswan openSUSE Tumbleweed 5.9.5-1.1
  • strongswan openSUSE Leap 15.3 5.8.2-11.24.1

opensuse advisories openSUSE-SU-2024:11808-1openSUSE-SU-2022:0492-1

  • strongswan Alpine 3.13 5.9.1-r2
  • strongswan Alpine 3.14 5.9.1-r3
  • strongswan Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 5.9.1-r4

alpine advisories ALPINE-CVE-2021-45079

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • strongswan CBL-Mariner 2.0 5.9.5-1

azure linux advisories AZL-8473

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-45079 updated cvss 9.1

strongswan: Incorrect Handling of Early EAP-Success Messages

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.76% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:P/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.