CVE-2023-21529
Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
CVSS
8.8
High
EPSS
62.1%
p99
KEV
YES
Apr 13, 2026
Exploit Today
80
0-100
Published: Feb 14, 2023 · Last modified: Aug 19, 2026 · CWE-502
62.1%EPSS · 30 days62.1%
2026-08-022026-08-31
Product
Microsoft / Exchange Server
Vulnerability
Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
Added to KEV
Apr 13, 2026
Remediate by
Apr 27, 2026
Known ransomware use
Yes
Summary description
Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Notes
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529 ; https://nvd.nist.gov/vuln/detail/CVE-2023-21529
Microsoft Exchange Server Remote Code Execution Vulnerability
- msrc.microsoft.comhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529
- msrc.microsoft.comhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529
- www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21529
- www.microsoft.comhttps://www.microsoft.com/en-us/security/blog/2026/04/06/storm-1175-focuses-gaze-on-vulnerable-web-facing-assets-in-high-tempo-medusa-ransomware-operations/
CVECVSSEPSSKEVRExploitTitleMod.
CVE-2026-81319—13.5%
——4Deserialization of Untrusted Data vulnerability in ash-project ash_cloak allows an attacker who can influence the bytes of an encrypted column to crash the BEAM node, by triggering unbounded atom creation or a decompression bomb during decryption.
AshCloak.Calculations.Decrypt decodes the decrypted binary with Ash.Helpers.non_executable_binary_to_term/1 without the :safe option, so atoms in the payload are interned during the decode and never garbage collected, and the term format's compressed form is inflated transparently. vault.decrypt!() is the only barrier and stops tampering only for an authenticated cipher. Cloak also ships the unauthenticated AES.CTR, whose ciphertext an attacker who knows their own plaintext can XOR into any same-length payload without the key, so an ordinary read of the forged column reaches the decoder. A few hundred kilobytes of distinct atoms exhausts the atom table, or a small compressed payload inflates to gigabytes.
This issue affects ash_cloak: from 0.1.0 before 0.4.0.20hCVE-2026-765476.6 MED15.7%
——5The User Profile Builder WordPress plugin before 4.0.1 does not validate the type of data being deserialized when importing a configuration file, allowing high privilege users such as administrators to conduct PHP Object Injection. The affected feature is a free add-on which is disabled by default, and no POP chain is present in the User Profile Builder WordPress plugin before 4.0.1 itself, so further impact requires a suitable gadget from another installed User Profile Builder WordPress plugin before 4.0.1 or .2dCVE-2026-55220—40.7%
——12Pimcore is an Open Source Data & Experience Management Platform. Prior to 11.5.19, 12.3.10, and 2026.1.6, Pimcore\Model\DataObject\ClassDefinition\Data\Hotspotimage::getDataFromResource() in models/DataObject/ClassDefinition/Data/Hotspotimage.php passes the field __hotspots object-store column to Pimcore\Tool\Serialize::unserialize() without an allowed-classes restriction after JSON decoding fails. An attacker with a separate capability to write crafted PHP serialized bytes into that column can instantiate available classes and trigger magic methods when an affected DataObject is loaded, which can produce arbitrary file writes or code execution through bundled gadget chains. The related ImageGallery, Block, and Video callers use the same fallback pattern, but the identified June fix changes the Hotspotimage caller only. This issue is fixed for Hotspotimage in versions 11.5.19, 12.3.10, and 2026.1.6.3dCVE-2026-817577.2 HIG36.1%
——11Author Remote Code Execution (RCE) in Rank Math SEO <= 1.0.276 versions.3dCVE-2026-822597.5 HIG30.0%
——9SvelteKit versions from 2.49.0 through 2.53.2 (fixed in 2.53.3) contain a deserialization expansion issue in the experimental form remote function. When an application enables experimental.remoteFunctions and uses the form function to process the files array without validating files.length or individual file sizes, an attacker can submit relatively small inputs that expand into very large file arrays, leading to expensive processing and denial of service.3dCVE-2026-8222210.0 CRI34.8%
——10Deserialization of Untrusted Data vulnerability in Liquid Web / StellarWP GiveWP allows Object Injection.
This issue affects GiveWP: from n/a through 4.16.7.1.3d