Linux Distros Unpatched Vulnerability : CVE-2026-123746

low Nessus Plugin ID 377463

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- The Symfony Security HTTP component AuthenticatorManager::authenticateUser() does not run the firewall user checker's checkPostAuth() method when a user is authenticated programmatically, allowing an account rejected by a custom user checker, such as an expired account, to be authenticated in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11.
AuthenticatorManager::authenticateUser() is used by UserAuthenticatorInterface::authenticateUser() and by the SecurityBundle's Security::login() to authenticate a user programmatically, but it does not dispatch the security.authentication.success event, on which checkPostAuth() runs. The fix for CVE-2024-50341 made Security::login() call checkPreAuth(), but checkPostAuth() was still skipped. As a result, an account rejected by a custom user checker in checkPostAuth() is refused by form login and the other authenticators of the firewall, but can still be authenticated programmatically. Applications are affected when they use a custom user checker that rejects users in checkPostAuth() and authenticate users programmatically, for example after a password reset or an e-mail verification link. A user whose account is rejected can then obtain an authenticated session through that flow. The default user checker does nothing in checkPostAuth(), so the default configuration is not affected. The fix makes AuthenticatorManager::authenticateUser() dispatch the security.authentication.success event once the token is created and before it is stored, as authentications through the firewall do, so that checkPostAuth() runs and can reject the user. (CVE-2026-123746)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: Low

ID: 377463

File Name: unpatched_CVE_2026_123746.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 11/7/2026

Updated: 11/7/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.52

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.4

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

CVSS Score Source: CVE-2026-123746

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9

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

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

CVSS v4

Risk Factor: Low

Base Score: 2.3

Threat Score: 0.6

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:13.0, cpe:/o:debian:debian_linux:14.0, p-cpe:/a:debian:debian_linux:symfony

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 11/6/2026

Reference Information

CVE: CVE-2026-123746

Detections

Analytics