CVE-2021-42564

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-11-30 · updated 2026-06-17
Weakness: CWE-601

Description

An open redirect through HTML injection in confidential messages in Cryptshare before 5.1.0 allows remote attackers (with permission to provide confidential messages via Cryptshare) to redirect targeted victims to any URL via the '<meta http-equiv="refresh"' substring in the editor parameter.

Affected products

Cryptshare Server: before 5.1.0 — fixed in 5.1.0

How to fix

Upgrade to a fixed version: Cryptshare Server 5.1.0. Check the vendor advisory for mitigations.

References

https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2021-057.txt
https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2021-057.txt

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