CVE-2026-123390 — Microsoft
HIGHCVE-2026-123390 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Description
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Detection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
The records we use list no fixed release for CVE-2026-123390. Check the upstream advisory for a patched version, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Frequently Asked Questions
Is CVE-2026-123390 in your dependencies?
Find it across your dependency tree, including transitive dependencies.