Type Vulnerability
Microsoft Exchange Server contains a deserialisation of untrusted data that allows an authenticated attacker to achieve remote code execution. Known-exploited catalogue reports exploitation in the wild.
Microsoft · Parser conflict
Microsoft Exchange Server Unsafe Deserialisation Vulnerability
CVE-2023-21529
What this means
This is rated high severity (8.8 out of 10). It is on the known-exploited catalogue, which means attacks using it have already been seen. Ask IT whether Microsoft Exchange Server is in your estate, and treat that as the priority.
Full vendor description
Microsoft Exchange Server Remote Code Execution Vulnerability
Scoring and exploitation
8.8/ 10
CVSS 3.1 base scoreHigh
Exploitable over the network with a low-privilege account, and no one has to click or open anything. High impact on confidentiality, integrity and availability.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploitability
Longer bar: easier to attack
Attack vectorNetworkAV:N
Attack complexityLowAC:L
Privileges requiredLowPR:L
User interactionNoneUI:N
ScopeUnchangedS:U
Impact
Longer bar: more harm
ConfidentialityHighC:H
IntegrityHighI:H
AvailabilityHighA:H
- Elevated attack likelihood (~59.3% in 30 days)Model estimate (): a probability signal, not confirmed exploitation
- Exploited in the wild
- Yes — confirmed exploitation (US CISA )
- Known
- Listed product
- Microsoft Exchange Server
Weaknesses
CWE-502
Affected products ()
- Microsoft Exchange Server
Show the raw CPE strings (4)
- cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_23:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_11:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_12:*:*:*:*:*:*
References
4 links from the CVE record, grouped by site; the vendor's advisory comes first.
msrc.microsoft.com1 linkVendor advisory
- CVE-2023-21529 (opens in a new tab)Patch · Vendor Advisory
cisa.gov1 link
- known-exploited-vulnerabilities-catalog (opens in a new tab)US Government Resource
microsoft.com1 link