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CVE-2021-44878

25
FAUCET Score

CVE-2021-44878 describes a vulnerability in pac4j versions up to 5.3.0 where the OpenID Connect provider fails to properly validate ID tokens when the "none" algorithm is supported. This allows an attacker to bypass token validation by injecting a malformed ID token with an empty signature. The vulnerability carries a CVSS score of 7.5 (HIGH), indicating a network-based attack with low complexity and high impact on integrity, as it allows for unauthorized access or manipulation. There is no confidentiality or availability impact. Currently, there is no evidence of active exploitation, nor are there publicly available exploit modules in Metasploit, Nuclei, or ExploitDB. Community discussion and media coverage for this CVE are minimal.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.5.5CPE matchmatch criteria
cpe:2.3:a:pac4j:pac4j:*:*:*:*:*:*:*:*
>= 5.0.0, < 5.3.1CPE matchmatch criteria
cpe:2.3:a:pac4j:pac4j:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.90%
Probability of exploitation in next 30 days
EPSS Percentile
55.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0089 is in the 31st percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
mavenpatch availablevia ghsa
Product: org.pac4j:pac4j-oidcFixed in: 4.5.5
mavenpatch availablevia ghsa
Product: org.pac4j:pac4j-oidcFixed in: 5.3.1

Vendor Advisories (1)

mavenGHSA-xhw6-hjc9-679mhigh

Pac4j token validation bypass if OpenID Connect provider supports none algorithm

Jan 8, 2022

References

github.com / pac4j/pac4j/commit/22b82ffd702a132d9f09da60362fc6264fc281ae
PatchThird Party Advisory
openid.net / specs/openid-connect-core-1_0.html
ProductThird Party Advisory
pac4j.org / blog/cve_2021_44878_is_this_serious.html
MitigationVendor Advisory