CVE-2026-31837
Prior to 1.29.1, 1.28.5, and 1.27.8, a user of Istio is impacted if the JWKS resolver becomes unavailable or the fetch fails, exposing hardcoded defaults regardless of use of the RequestAuthentication resource.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.38%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Istio is an open platform to connect, manage, and secure microservices. Prior to 1.29.1, 1.28.5, and 1.27.8, a user of Istio is impacted if the JWKS resolver becomes unavailable or the fetch fails, exposing hardcoded defaults regardless of use of the RequestAuthentication resource. This vulnerability is fixed in 1.29.1, 1.28.5, and 1.27.8.
- CVSS 4.0
- 8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.38% probability · 31th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-200, CWE-1392
- Affected
- istio/istio
- Source
- security-advisories@github.com
References
- https://github.com/istio/istio/security/advisories/GHSA-v75c-crr9-733cVendor Advisory
- https://access.redhat.com/errata/RHSA-2026:10184
- https://access.redhat.com/errata/RHSA-2026:5948
- https://access.redhat.com/errata/RHSA-2026:5950
- https://access.redhat.com/errata/RHSA-2026:5952
- https://access.redhat.com/security/cve/CVE-2026-31837
- https://bugzilla.redhat.com/show_bug.cgi?id=2446344
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31837.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.