Amazon Linux 2023 : ecs-service-connect-agent (ALAS2023-2026-2149)

high Nessus Plugin ID 345777

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Synopsis

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

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-2149 advisory.

An Envoy proxy handling HTTP/3 connections can dereference a null transport socket option during the selection of a connection pool. This null pointer dereference is a CWE-476 flaw that may cause the process to crash or terminate unexpectedly, leading to a denial of service for the services routed through the affected Envoy instance. The vulnerability is triggered when a client initiates an HTTP/3 session that exercises the connection-pool selection logic, which may provide the attacker a remote execution path to disrupt the proxy. (CVE-2026-48521)

Fixed a use-after-free in the ext_authz raw HTTP client where completing an authorization request could destroy the client while its completion handler was still executing. (CVE-2026-50572)

Fixed path matching for paths containing per-segment parameters, where Envoy and backends could select different resources for the same request and bypass path-based selection or authentication.
(CVE-2026-73511)

Fixed a use-after-free in the QUIC HTTP datagram handler where late HTTP/3 datagrams could reference a stream decoder that was already destroyed or replaced. (CVE-2026-73512)

Fixed a heap use-after-free where an untrusted upstream could send HTTP/2 response trailers without the END_STREAM flag to an Envoy instance using oghttp2, corrupting stream state and terminating the process.
(CVE-2026-73513)

Fixed a stored cross-site scripting issue in the HTML stats interface (/stats?format=html) where dynamically named statistics could introduce attacker-controlled content. (CVE-2026-73546)

Fixed an abnormal process termination in the ext_authz filter when processing CONNECT requests without a :path pseudo-header. (CVE-2026-73547)

Fixed cross-user response poisoning involving generic, non-WebSocket HTTP upgrades, where request payload sent before an upgrade was accepted could contaminate a shared upstream connection. (CVE-2026-73548)

Fixed an abnormal process termination for scoped IPv6 client addresses in original DST clusters with HTTP/3. (CVE-2026-73549)

Fixed an HTTP/2 memory-exhaustion issue where discarded duplicate Host headers were not counted toward request-header size and count limits. (CVE-2026-73550)

Fixed URL normalization of dot and dot-dot path segments containing parameters, which could cause access- control components and upstream applications to interpret a request path differently. (CVE-2026-73551)

Fixed an issue where safe_regex matching treated accepted non-UTF-8 HTTP header bytes as a non-match; in RBAC policies using negative matching this could fail open and allow access to a protected resource.
(CVE-2026-73552)

Fixed an authorization bypass when ignore_path_parameters_in_path_matching was enabled, where a path such as /admin;x could bypass an RBAC policy for /admin while still reaching the protected route.
(CVE-2026-73553)

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

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

Solution

Run 'dnf update ecs-service-connect-agent --releasever 2023.12.20260914' or or 'dnf update --advisory ALAS2023-2026-2149 --releasever 2023.12.20260914' to update your system.

Plugin Details

Severity: High

ID: 345777

File Name: al2023_ALAS2023-2026-2149.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 9/14/2026

Updated: 9/14/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.3

Percentile: 50.67

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.2

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

CVSS Score Source: CVE-2026-73553

CVSS v3

Risk Factor: High

Base Score: 8.6

Temporal Score: 7.5

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

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

Vulnerability Information

CPE: cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:ecs-service-connect-agent

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

Exploit Ease: No known exploits are available

Patch Publication Date: 9/14/2026

Vulnerability Publication Date: 9/14/2026

Reference Information

CVE: CVE-2026-48521, CVE-2026-50572, CVE-2026-73511, CVE-2026-73512, CVE-2026-73513, CVE-2026-73546, CVE-2026-73547, CVE-2026-73548, CVE-2026-73549, CVE-2026-73550, CVE-2026-73551, CVE-2026-73552, CVE-2026-73553

Detections

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