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CVE-2021-45079

30
FAUCET Score

CVE-2021-45079 is a critical vulnerability affecting strongSwan versions prior to 5.9.5, as well as canonical, debian, and fedoraproject distributions. It allows a malicious responder to bypass authentication by sending an EAP-Success message prematurely, potentially compromising client and server authentication in IKEv2 EAP-only scenarios. With a CVSS score of 9.1 (CRITICAL), this vulnerability is easily exploitable over the network with low attack complexity, leading to high confidentiality and availability impacts. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.1.2, < 5.9.5CPE matchmatch criteria
cpe:2.3:a:strongswan:strongswan:*:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:a:fedoraproject:extra_packages_for_enterprise_linux:7.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.78%
Probability of exploitation in next 30 days
EPSS Percentile
84.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0278 is in the 76th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (8)

microsoftpatch availablevia msrc
Product: 18901-16820Fixed in: 5.7.2-5
microsoftpatch availablevia msrc
Product: 18902-16823Fixed in: 5.9.5-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 5.7.2-5
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 5.7.2-5
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 5.9.5-1
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 5.9.5-1
microsoftpatch availablevia msrc
Product: cm1 strongswan 5.7.2-5 on CBL Mariner 1.0Fixed in: 5.7.2-5
microsoftpatch availablevia msrc
Product: cbl2 strongswan 5.9.5-1 on CBL Mariner 2.0Fixed in: 5.9.5-1

Vendor Advisories (2)

microsoft2022-Feb/CVE-2021-45079

CVE-2021-45079

Feb 8, 2022
microsoft2022-Jan/CVE-2021-45079Critical

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.

Jan 11, 2022

References

strongswan.org / blog/2022/01/24/strongswan-vulnerability-%28cve-2021-45079%29.html