CVE-2026-31837
Istio JWKS resolver auth bypass in older versions
Is CVE-2026-31837 being exploited?
Not confirmed. CVE-2026-31837 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 0.38% probability of exploitation in the next 30 days.
How severe is CVE-2026-31837?
CVE-2026-31837 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-2026-31837?
Yes. A fix has been recorded for CVE-2026-31837. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-31837 affect?
CVE-2026-31837 affects Istio <1.29.1, Istio <1.28.5, Istio <1.27.8. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-31837?
Upgrade to fixed versions (1.29.1, 1.28.5, or 1.27.8).
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Auth bypass via JWKS resolver failure; defaults used, enabling unauthorized access to services.
Patch when possible
- affected>= 1.29.0-alpha.0 and < 1.29.1
- affected>= 1.28.0-alpha.0 and < 1.28.5
- affected< 1.27.8
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.