How severe is CVE-2021-36806?

CVE-2021-36806 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-36806 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-36806?

CVE-2021-36806 affects Sophos Email Appliance. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-36806?

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

When was CVE-2021-36806 published?

CVE-2021-36806 was published on 2023-11-30 and last updated on 2026-06-17.

CVE-2021-36806

CVE-2021-36806 is a medium-severity vulnerability in Sophos Email Appliance with a CVSS 3.x base score of 4.7. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 4.7)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Sophos Email Appliance
Published: 2023-11-30
Last modified: 2026-06-17

Description

A reflected XSS vulnerability allows an open redirect when the victim clicks a malicious link to an error page on Sophos Email Appliance older than version 4.5.3.4.

Frequently asked questions

What is CVE-2021-36806?: A reflected XSS vulnerability allows an open redirect when the victim clicks a malicious link to an error page on Sophos Email Appliance older than version 4.5.3.4.
How severe is CVE-2021-36806?: CVE-2021-36806 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-36806 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-36806?: CVE-2021-36806 affects Sophos Email Appliance. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-36806?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-36806 published?: CVE-2021-36806 was published on 2023-11-30 and last updated on 2026-06-17.

References

https://community.sophos.com/email-appliance/b/blog/posts/sophos-email-appliance-version-4-5-3-4-released

Affected products (1)

cpe:2.3:a:sophos:email_appliance:*:*:*:*:*:*:*:*

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