How severe is CVE-2021-20875?

CVE-2021-20875 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-20875 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20875?

CVE-2021-20875 primarily affects Groupsession. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20875?

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

When was CVE-2021-20875 published?

CVE-2021-20875 was published on 2021-12-24 and last updated on 2026-06-17.

CVE-2021-20875

CVE-2021-20875 is a medium-severity vulnerability in Groupsession with a CVSS 3.x base score of 6.1. 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-601.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 5.8
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-601
Affected product: Groupsession
Published: 2021-12-24
Last modified: 2026-06-17

Description

Open redirect vulnerability in GroupSession Free edition ver5.1.1 and earlier, GroupSession byCloud ver5.1.1 and earlier, and GroupSession ZION ver5.1.1 and earlier allows a remote unauthenticated attacker to redirect users to arbitrary web sites and conduct phishing attacks by having a user to access a specially crafted URL.

Frequently asked questions

What is CVE-2021-20875?: Open redirect vulnerability in GroupSession Free edition ver5.1.1 and earlier, GroupSession byCloud ver5.1.1 and earlier, and GroupSession ZION ver5.1.1 and earlier allows a remote unauthenticated attacker to redirect users to arbitrary web sites and conduct phishing attacks by having a user to access a specially crafted URL.
How severe is CVE-2021-20875?: CVE-2021-20875 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-20875 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20875?: CVE-2021-20875 primarily affects Groupsession. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20875?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20875 published?: CVE-2021-20875 was published on 2021-12-24 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:groupsession:groupsession:*:*:*:*:cloud:*:*:*
cpe:2.3:a:groupsession:groupsession:*:*:*:*:free:*:*:*
cpe:2.3:a:groupsession:groupsession:*:*:*:*:zion:*:*:*

More vulnerabilities in Groupsession

CVE-2021-20874 — High (CVSS 7.5): Incorrect permission assignment for critical resource vulnerability in GroupSession Free edition ver5.1.1 and earlier,…
CVE-2021-20876 — Medium (CVSS 6.8): Path traversal vulnerability in GroupSession Free edition ver5.1.1 and earlier, GroupSession byCloud ver5.1.1 and…
CVE-2017-2165 — Medium (CVSS 6.5): GroupSession versions 4.6.4 and earlier allows remote authenticated attackers to bypass access restrictions to obtain…
CVE-2025-65120 — Medium (CVSS 6.1): Reflected cross-site scripting vulnerability exists in GroupSession Free edition prior to ver5.7.1, GroupSession…
CVE-2025-57883 — Medium (CVSS 6.1): Reflected cross-site scripting vulnerability exists in GroupSession Free edition prior to ver5.3.0, GroupSession…
CVE-2025-54407 — Medium (CVSS 6.1): Stored cross-site scripting vulnerability exists in GroupSession Free edition prior to ver5.3.0, GroupSession byCloud…

All CVEs affecting Groupsession →

Other CWE-601 (Open Redirect) vulnerabilities

CVE-2018-3774 — Critical (CVSS 10.0): Incorrect parsing in url-parse <1.4.3 returns wrong hostname which leads to multiple vulnerabilities such as SSRF, Open…
CVE-2019-25282 — Critical (CVSS 9.8): V-SOL GPON/EPON OLT Platform v2.03 contains an open redirect vulnerability in the script that allows attackers to…
CVE-2020-36912 — Critical (CVSS 9.8): Plexus anblick Digital Signage Management 3.1.13 contains an open redirect vulnerability in the 'PantallaLogin' script…
CVE-2025-43526 — Critical (CVSS 9.8): This issue was addressed with improved URL validation. This issue is fixed in Safari 26.2, macOS Tahoe 26.2. On a Mac…
CVE-2025-55031 — Critical (CVSS 9.8): Malicious pages could use Firefox for iOS to pass FIDO: links to the OS and trigger the hybrid passkey transport. An…
CVE-2024-22891 — Critical (CVSS 9.8): Nteract v.0.28.0 was discovered to contain a remote code execution (RCE) vulnerability via the Markdown link.

Browse all CWE-601 (Open Redirect) vulnerabilities →