CVE-2023-21529 (Microsoft Exchange Server) is in the CISA Known Exploited Vulnerabilities catalog since 2026-04-13. Used in ransomware. Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker… See the required fix, due date and advisories.
CVE-2023-21529 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2026-04-13. Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Wording published by CISA for this catalog entry. It is the baseline action, not a decision about your environment: whether this exposure matters for you depends on where the affected component runs, what it is exposed to and who owns it.
A catalog entry tells you a vulnerability is being exploited somewhere. It does not tell you whether it matters in your estate, who owns the fix, or what evidence an auditor will ask for later. That is the work VulnTrek does: it takes findings from the tools you already run, decides which exposure actually matters, routes it to an owner, keeps remediation human-approved and retains the lineage as evidence.
Sourced from public upstream advisories (CISA KEV, ENISA EUVD, vendor PSIRTs) mirrored daily. Informational only — not a remediation decision, not legal advice, and the absence of a record is not evidence of safety.