CVE intelligence

CVE-2026-66858

Vulnerability intelligence

Published Oct 2, 2026Sources checked Oct 7, 2026

8.7HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-66858 and is rated High severity with a CVSS score of 8.7. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Oct 5, 2026

Release Notes

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-66858?

The protocol skip routine in several Apache Thrift bindings did not apply the binding's recursion limit, so a message that nests unknown fields deeply enough can exhaust the stack. Affected: the Python C++ accelerator (the pure-Python protocols are not affected), the PHP library and its thrift_protocol extension, and the Perl, Lua, Smalltalk and OCaml libraries. This issue affects Apache Thrift: before 0.25.0. Users are recommended to upgrade to version 0.25.0, which fixes the issue.

Source: NVD