CVE-2024-21410 — Microsoft Exchange Server Privilege Escalation Vulnerability
Microsoft Exchange Server Elevation of Privilege Vulnerability
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Confirmed exploitation (CISA KEV)+35
- Public exploit/PoC (github)+6
- EPSS 12.6% (30-day exploitation probability)+14
- Technical severity (critical)+10
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — msrc.microsoft.com (NIST National Vulnerability Database)
CISA required action CISA
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
US federal deadline: Mar 7, 2024 — passed 953 day(s) ago
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Microsoft Exchange Server, Microsoft Microsoft Exchange Server 2016 Cumulative Update 23, Microsoft Microsoft Exchange Server 2019 Cumulative Update 13…).
- Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- EPSS ahead of 96% of scored CVEs: prioritize it in the patch queue.
- Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Microsoft | Exchange Server | version 2016-cumulative_update_23version 2019-cumulative_update_13version 2019-cumulative_update_14 | Vulnerable | NIST National Vulnerability Database |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 23 | ≥ 15.01.0 and < 15.01.2507.037 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 13 | ≥ 15.02.0 and < 15.2.1544.004 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 14 | ≥ 15.02.0 and < 15.2.1544.004 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 9.8 | CVSS 3.1 | Critical | 3.9 | 5.9 | secure@microsoft.com via NIST National Vulnerability Database |
| 9.8 | CVSS 3.1 | Critical | — | — | GitHub, Inc. via GitHub Security Advisories |
| 9.8 | CVSS 3.1 | Critical | — | — | microsoft via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: secure@microsoft.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
CISA KEV details CISA
CISA lists a CVE once it has evidence of exploitation against real targets.
CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.
Public exploits, PoCs and detection templates
Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.
Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.
EPSS over time FIRST
Oct 12, 2026 → Oct 15, 2026 · 4 reading(s) · max 12.56%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.
- Hunt retroactively in logs from before Feb 15, 2024 (KEV listing): exploitation may have started earlier.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · microsoft/microsoft exchange server 2016 cumulative update 23, microsoft/microsoft exchange server 2019 cumulative updat
- SSVC assessment updated
- Record published
- Fix documented
- Affected products added · microsoft/exchange server
- CVSS changed · 9.8
- Source status changed · → Analyzed
- Added to CISA KEV (detected)
- Record created in this database
- 2024
- Added to CISA KEV catalog
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 13, 2026 – Oct 13, 2026
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
4 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-87696 Microsoft Exchange Server Elevation of Privilege Vulnerability 2d
- High CVE-2026-87695 Microsoft Exchange Server Elevation of Privilege Vulnerability 2d
- High CVE-2026-87692 Microsoft Exchange Server Elevation of Privilege Vulnerability 2d
- High CVE-2026-77910 Microsoft Exchange Server Elevation of Privilege Vulnerability 2d
- High CVE-2026-70571 Microsoft Exchange Server Remote Code Execution Vulnerability 2d
- Critical CVE-2026-70279 Microsoft Exchange Server Spoofing Vulnerability 2d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2024-21410 is "Microsoft Exchange Server Privilege Escalation Vulnerability", rated Critical. It affects Exchange Server (Microsoft); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 9.8 describes technical severity. EPSS 12.56% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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