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CVE-2015-6835

CRITICAL severity · CVSS 9.8
9.8CVSS CRITICAL

Summary

The session deserializer in PHP before 5.4.45, 5.5.x before 5.5.29, and 5.6.x before 5.6.13 mishandles multiple php_var_unserialize calls, which allow remote attackers to execute arbitrary code or cause a denial of service (use-after-free) via crafted session content.

Impact & exploitability

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)23%

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

Affected products we track (1)

PHP

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Last checked: Wed, 10 Jun 2026 22:18:30 UTC