CVE-2026-31838

mediumpriority · track · 21OT risk · elevatedEPSS 0.002 · 13 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.22% (13th) EPSS

CVSS 5.3 · medium

Is it mine?

16 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · cert_bund · nvd

EPSS · scored 2026-10-26

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.

cvss

Technical severity, 0–10. One row per scoring source.

6.9

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 2.7–6.9

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 1.4

v4.06.9mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:Nsecondary · ENISA EU

v4.06.9mediumCVSS: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:Xsecondary · security-advisories@github.com

v4.02.7lowCVSS: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:U/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:Xsecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-863US

affected products (16)

Products and version ranges known to be affected.

Amazon Linux 2all versionscert_bundDEcpe:/o:amazon:linux_2:-
Google Cloud Platform Envoy Proxyall versionscert_bundDEcpe:/a:google:cloud_platform:envoy_proxy
Google Cloud Platform Istioall versionscert_bundDEcpe:/a:google:cloud_platform:istio
Google Cloud Platform Service Mesh <1.26.8-asm.3all versionscert_bundDE
Google Cloud Platform Service Mesh <1.27.8-asm.7all versionscert_bundDE
Google Cloud Platform Service Mesh <1.28.5-asm.9all versionscert_bundDE
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
Google Cloud Platform≤ Service Mesh <1.26.8-asm.3cert_bundDE
Google Cloud Platform≤ Service Mesh <1.27.8-asm.7cert_bundDE
Google Cloud Platform≤ Service Mesh <1.28.5-asm.9cert_bundDE
istio istio≤ < 1.27.8enisa_euvdEU
istio istio1.28.0-alpha.0, → 1.28.5enisa_euvdEU
istio istio1.29.0-alpha.0, → 1.29.1enisa_euvdEU
istio istio< 1.27.8nvdUScpe:2.3:a:istio:istio:*:*:*:*:*:*:*:*
istio istio1.28.0 → 1.28.5nvdUScpe:2.3:a:istio:istio:*:*:*:*:*:*:*:*
istio istio1.29.0 → 1.29.1nvdUScpe:2.3:a:istio:istio:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-0704Google Cloud Platform Envoy Proxy, Istio und Service Mesh: Mehrere SchwachstellenDeutsch2026-03-11csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Google Cloud Platform ausnutzen, um Sicherheitsvorkehrungen zu umgehen, vertrauliche Informationen offenzulegen oder einen Denial-of-Service-Zustand zu verursachen.

also known as (2)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund nvd NVD CVE.org MITRE

published 2026-03-10modified 2026-06-17

references (6)

External citations — patches, advisories, analysis.

scry

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