CVE-2026-31837

Q: How do I fix CVE-2026-31837?

Upgrade istio to 1.27.8 or later.

Q: Is CVE-2026-31837 being actively exploited?

Not that we know of. CVE-2026-31837 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.70% is the estimated probability that it will be exploited in the next 30 days. That is higher than 52% of all scored CVEs.

Q: How severe is CVE-2026-31837?

CVE-2026-31837 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-31837 affect?

Published advisories record a fix for istio (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

HIGH

7.5

CVSS v3

NVD

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.

CWE-200Information Exposure CWE-1392

How to fix

Remediation Available

istioNVD

Affected:< 1.27.8Fixed in:1.27.8CVE-2026-31837derived from NVD

Affected:>= 1.28.0, < 1.28.5Fixed in:1.28.5CVE-2026-31837derived from NVD

Affected:>= 1.29.0, < 1.29.1Fixed in:1.29.1CVE-2026-31837derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

0.70%probability of exploitation in 30 days

52ndpercentile

Moderate risk: more likely to be exploited than 52% of all known CVEs.

References

Vendor Advisory1

github.com

Other references7

Related Vulnerabilities

Other CWE-200 (Information Exposure) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-24919	High	8.6	100%	KEV + Ransom	-
CVE-2020-14181	Medium	5.3	100%	-	Fix
CVE-2021-34429	Medium	5.3	99%	-	Fix
CVE-2018-11409	Medium	5.3	98%	-	-
CVE-2021-41277	Critical	10.0	97%	KEV	-
CVE-2016-2183	High	7.5	95%	-	Fix

Common questions

How do I fix CVE-2026-31837?

Upgrade istio to 1.27.8 or later.

Is CVE-2026-31837 being actively exploited?

Not that we know of. CVE-2026-31837 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.70% is the estimated probability that it will be exploited in the next 30 days. That is higher than 52% of all scored CVEs.

How severe is CVE-2026-31837?

CVE-2026-31837 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-31837 affect?

Published advisories record a fix for istio (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-31837

Markdown

[![CVE-2026-31837](https://tridentstack.com/cve/badge/CVE-2026-31837.svg)](https://tridentstack.com/cve/CVE-2026-31837)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-31837"><img src="https://tridentstack.com/cve/badge/CVE-2026-31837.svg" alt="CVE-2026-31837"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Run a free CVE scan on your fleet Start freeThis CVE lookup is free and always will be.

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-20.