How severe is CVE-2021-28963?

CVE-2021-28963 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-28963 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28963?

CVE-2021-28963 primarily affects Shibboleth Service Provider. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-28963?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-28963 published?

CVE-2021-28963 was published on 2021-03-22 and last updated on 2026-06-17.

CVE-2021-28963

CVE-2021-28963 is a medium-severity vulnerability in Shibboleth Service Provider with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-74.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-74
Affected product: Shibboleth Service Provider
Published: 2021-03-22
Last modified: 2026-06-17

Description

Shibboleth Service Provider before 3.2.1 allows content injection because template generation uses attacker-controlled parameters.

Frequently asked questions

What is CVE-2021-28963?: Shibboleth Service Provider before 3.2.1 allows content injection because template generation uses attacker-controlled parameters.
How severe is CVE-2021-28963?: CVE-2021-28963 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-28963 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28963?: CVE-2021-28963 primarily affects Shibboleth Service Provider. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-28963?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-28963 published?: CVE-2021-28963 was published on 2021-03-22 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:shibboleth:service_provider:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

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