How severe is CVE-2021-36580?

CVE-2021-36580 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-2021-36580 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-36580?

CVE-2021-36580 primarily affects Icewarp Icewarp Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-36580?

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

When was CVE-2021-36580 published?

CVE-2021-36580 was published on 2023-07-27 and last updated on 2026-07-05.

CVE-2021-36580

CVE-2021-36580 is a medium-severity vulnerability in Icewarp Icewarp Server 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)
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-601
Affected product: Icewarp Icewarp Server
Published: 2023-07-27
Last modified: 2026-07-05

Description

Open Redirect vulnerability exists in IceWarp MailServer IceWarp Server Deep Castle 2 Update 1 (13.0.1.2) via the referer parameter.

Frequently asked questions

What is CVE-2021-36580?: Open Redirect vulnerability exists in IceWarp MailServer IceWarp Server Deep Castle 2 Update 1 (13.0.1.2) via the referer parameter.
How severe is CVE-2021-36580?: CVE-2021-36580 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-2021-36580 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-36580?: CVE-2021-36580 primarily affects Icewarp Icewarp Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-36580?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-36580 published?: CVE-2021-36580 was published on 2023-07-27 and last updated on 2026-07-05.

References

Affected products (2)

cpe:2.3:a:icewarp:icewarp_server:*:*:*:*:*:*:*:*
cpe:2.3:a:icewarp:mail_server:*:*:*:*:*:*:*:*

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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.

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