# CVE-2026-31837: Istio JWKS resolver to prevent private key material from being exposed when JWKS fetch fails.

> Istio users face exposure of hardcoded private key material when JWKS fetches fail, requiring an upgrade to secure service mesh authentication.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Mar 2026
- **Updated:** 20 Jul 2026
- **Also known as:** CLEANSTART-2026-IN05480, GHSA-v75c-crr9-733c, MINI-7wj6-6v2g-rcjr, MINI-82qv-2q2m-c9jp, MINI-86wf-pgj9-g3jj, MINI-87ph-2c98-qjvg, MINI-963h-xwc6-6cx6, MINI-c3pq-v7p8-4jv7, MINI-cxf6-672q-vv23, MINI-fhw9-vpfh-jq6m, MINI-h66q-g69m-5r5p, MINI-jm92-hjx6-v5w9, MINI-pmpp-4ppm-p558, MINI-qp73-3mq2-w73j, MINI-rmhh-2vx3-7v87, MINI-v8jc-r8mv-xpp2, MINI-vgpj-8rxp-3pg7, MINI-x9wx-q7wp-2fq2

## What is CVE-2026-31837?

CVE-2026-31837 is a high-severity vulnerability in istio, published on 10 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-1392 (Use of Default Credentials), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-31837?

It affects 1 product.


Products: Istio Istio.

## How do I fix CVE-2026-31837?

Upgrade to a fixed version.

## Is CVE-2026-31837 being exploited?

There is no known exploitation of CVE-2026-31837 in the wild and no public exploit code.

## Other vulnerabilities in istio

- [CVE-2021-31921](https://insights.sbomify.com/CVE-2021-31921/): Missing authorization in n/a (critical 9.8)
- [CVE-2021-34824](https://insights.sbomify.com/CVE-2021-34824/): Information disclosure in n/a (high 8.8)
- [CVE-2021-39155](https://insights.sbomify.com/CVE-2021-39155/): Authorization Policy Bypass Due to Case Insensitive Host Comparison (high 8.3)
- [CVE-2021-39156](https://insights.sbomify.com/CVE-2021-39156/): Fragments in Path May Lead to Authorization Policy Bypass (high 8.1)
- [CVE-2022-39388](https://insights.sbomify.com/CVE-2022-39388/): Istio may allow identity impersonation if user has localhost access (high 7.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31837 and fix it if it is affected.

What it is: CVE-2026-31837 is a high-severity vulnerability in istio, published on 10 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-31837 in the wild and no public exploit code.

Affected product: istio. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-31837/ (Markdown: https://insights.sbomify.com/CVE-2026-31837/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31837
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31837
- OSV: https://osv.dev/vulnerability/CVE-2026-31837

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31837/
Summaries are generated and may contain mistakes; the official description above is the record.