Amazon Linux 2023 : credentials-fetcher (ALAS2023-2026-1551)

critical Nessus Plugin ID 306223

Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1551 advisory.

gRPC-Go is the Go language implementation of gRPC. Versions prior to 1.79.3 have an authorization bypass resulting from improper input validation of the HTTP/2 `:path` pseudo-header. The gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, deny rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback allow rule was present. This affects gRPC-Go servers that use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`; AND that have a security policy contains specific deny rules for canonical paths but allows other requests by default (a fallback allow rule). The vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server. The fix in version 1.79.3 ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string. While upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods: Use a validating interceptor (recommended mitigation); infrastructure-level normalization; and/or policy hardening. (CVE-2026-33186)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'dnf update credentials-fetcher --releasever 2023.11.20260413' or or 'dnf update --advisory ALAS2023-2026-1551 --releasever 2023.11.20260413' to update your system.

Plugin Details

Severity: Critical

ID: 306223

File Name: al2023_ALAS2023-2026-1551.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 4/13/2026

Updated: 4/13/2026

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 7.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N

CVSS Score Source: CVE-2026-33186

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 8.2

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:credentials-fetcher, cpe:/o:amazon:linux:2023

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/13/2026

Vulnerability Publication Date: 3/18/2026

Reference Information

CVE: CVE-2026-33186

Detections

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