CVE-2026-45077: symfony Insecure Deserialization — Fix

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.

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CVSS v3.1 Score

8.6

HIGH

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

EPSS — Exploit Prediction

0.0045

Probability of exploitation

0.36%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-502 Deserialization of Untrusted Data

CWE-668 CWE-668

Affected Products

Vendor	Product	Versions
sensiolabs	symfony	< 5.4.52
sensiolabs	symfony	6.0.0 — 6.4.40
sensiolabs	symfony	7.0.0 — 7.4.12
sensiolabs	symfony	8.0.0 — 8.0.12

References

Advisories & Patches

https://github.com/symfony/symfony/commit/0891b2f293896c488e26943dc034334364b77fc4 https://github.com/symfony/symfony/security/advisories/GHSA-m7v2-7gxm-vc2v

Other References

https://github.com/symfony/symfony/releases/tag/v5.4.52 https://github.com/symfony/symfony/releases/tag/v6.4.40 https://github.com/symfony/symfony/releases/tag/v7.4.12 https://github.com/symfony/symfony/releases/tag/v8.0.12

Frequently Asked Questions

What is CVE-2026-45077? +

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. It has a CVSS v3.1 base score of 8.6 (HIGH).

How severe is CVE-2026-45077? +

CVE-2026-45077 has a CVSS v3.1 score of 8.6 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0045, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-45077? +

CVE-2026-45077 affects products from sensiolabs, specifically: symfony. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-45077? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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