Is CVE-2026-31838 actively exploited?

No active exploitation of CVE-2026-31838 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-31838 be exploited remotely?

Yes. CVE-2026-31838 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-31838?

CVE-2026-31838 has a CVSS score of 6.9 (MEDIUM).

HOME VULNERABILITIESCVE-2026-31838

MEDIUM

CVE-2026-31838

CWE-863Published: March 10, 2026· Updated: Mar 11, 2026

6.9

CVSS v3.1

EPSS:0.04%probability of exploitation in 30 daysPercentile:12.2th

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 vulnerability in Envoy RBAC header matching could allow authorization policy bypass when policies rely on HTTP headers that may contain multiple values. An attacker could craft requests with multiple header values in a way that causes Envoy to evaluate the header differently than intended, potentially bypassing authorization checks. This may allow unauthorized requests to reach protected services when policies depend on such header-based matching conditions. This vulnerability is fixed in 1.29.1, 1.28.5, and 1.27.8.

NVD Source

Technical Analysis

CVE-2026-31838 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

User InteractionNone

ScopeX

Impact

Confidentiality

Integrity

Availability

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X