Apache Thrift is a widely used RPC framework across industries; a high-severity flaw can crash services and affect many deployments.
CVE-2026-66858
Apache Thrift stack exhaustion via deeply nested unknown fields in several bindings (pre-0.25.0).
Is CVE-2026-66858 being exploited?
Not confirmed. CVE-2026-66858 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.26% probability of exploitation in the next 30 days.
How severe is CVE-2026-66858?
CVE-2026-66858 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-66858?
Yes. A fix has been recorded for CVE-2026-66858. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-66858 affect?
CVE-2026-66858 affects Apache Thrift < 0.25.0, Python C++ accelerator (not pure-Python), PHP library & thrift_protocol extension, Perl library, and 3 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-66858?
Upgrade to Apache Thrift 0.25.0; block/restrict untrusted Thrift traffic.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote denial-of-service: crafted Thrift messages bypass recursion limits to exhaust the stack and crash processes/services.
Patch when possible
- affected< 0.25.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.