What’s Vulnerable › Vulnerabilities

CVE-2018-11386

• Severity: medium (CVSS 5.9 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-06-13 · updated 2026-06-17
• Weakness: CWE-613

Description

An issue was discovered in the HttpFoundation component in Symfony 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11. The PDOSessionHandler class allows storing sessions on a PDO connection. Under some configurations and with a well-crafted payload, it was possible to do a denial of service on a Symfony application without too much resources.

Affected products

• Debian Linux: 9.0
• symfony: from 2.7.0 before 2.7.48; from 2.8.0 before 2.8.41; from 3.3.0 before 3.3.17; from 3.4.0 before 3.4.11; from 4.0.0 before 4.0.11 — fixed in 2.7.48, 2.8.41, 3.3.17, 3.4.11, 4.0.11

How to fix

Upgrade to a fixed version: symfony 2.7.48, 2.8.41, 3.3.17, 3.4.11. Check the vendor advisory for mitigations.

References

• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G4XNBMFW33H47O5TZGA7JYCVLDBCXAJV/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UBQK7JDXIELADIPGZIOUCZKMAJM5LSBW/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WU5N2TZFNGXDGMXMPP7LZCWTFLENF6WH/
• https://symfony.com/blog/cve-2018-11386-denial-of-service-when-using-pdosessionhandler
• https://www.debian.org/security/2018/dsa-4262
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G4XNBMFW33H47O5TZGA7JYCVLDBCXAJV/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UBQK7JDXIELADIPGZIOUCZKMAJM5LSBW/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WU5N2TZFNGXDGMXMPP7LZCWTFLENF6WH/
• https://symfony.com/blog/cve-2018-11386-denial-of-service-when-using-pdosessionhandler
• https://www.debian.org/security/2018/dsa-4262

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