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CVE-2021-28963

20
FAUCET Score

CVE-2021-28963 describes a content injection vulnerability in Shibboleth Service Provider versions prior to 3.2.1, where attacker-controlled parameters can be used during template generation. This medium-severity vulnerability (CVSS 5.3) has a low attack complexity and can lead to information integrity impact, but does not affect confidentiality or availability. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.2.1CPE matchmatch criteria
cpe:2.3:a:shibboleth:service_provider:*:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.29%
Probability of exploitation in next 30 days
EPSS Percentile
67.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0129 is in the 47th percentile among its peer group of 23,725 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

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

Remediation

Remediation records are not available for this CVE.

References

bugs.debian.org / 985405
Mailing ListThird Party Advisory
git.shibboleth.net / view
issues.shibboleth.net / jira/browse/SSPCPP-922
Issue TrackingPatchVendor Advisory
shibboleth.net / community/advisories/secadv_20210317.txt
Vendor Advisory
debian.org / security/2021/dsa-4872
Mailing ListThird Party Advisory