CVE-2026-45077: Symfony: Unauthenticated PHP Object Deserialization in MonologBridge server:log Listener

Description

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, the server:log listener (Symfony\Bridge\Monolog\Command\ServerLogCommand) binds to 0.0.0.0:9911 by default and processes each received frame with unserialize(base64_decode($message)) without authentication, integrity checks, or an allowed_classes allowlist, allowing any reachable host to submit attacker-chosen serialized PHP payloads that can crash the listener and may trigger object-injection gadget effects. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

Low

Integrity

Low

Availability

High

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)0.7% · higher than 52% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

MO

monolog-bridge · symfony

< 5.4.52; >= 6.0.0-BETA1, < 6.4.40; >= 7.0.0-BETA1, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor

SY

symfony · symfony

< 5.4.52; >= 6.0.0-BETA1, < 6.4.40; >= 7.0.0-BETA1, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor, NVD