CVE-2015-6835
Status: ModifiedCritical (9.8)—Exploit
Severity9.8Critical · CVSS 3.0
Exploitation probability36 %higher than 98% of CVEs
Active exploitationNonot in the CISA catalog
Public exploitAvailablePublished on Exploit-DB · Proof of concept on GitHub (unverified)
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.
CVSS
- Base score
- 9.8
- Version
- 3.0
- Vector
- CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 36 %
- Percentile among all scored CVEs
- 98
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Public exploits
Exploit code or detection templates are publicly available. This is not the same as confirmed active exploitation (KEV), but it raises the risk: patch with priority.
- Published on Exploit-DB · PHP Session Deserializer - Use-After-Free (9/9/2015)
- Proof of concept on GitHub (unverified) · List of proofs of concept on GitHub
⚠️ GitHub proofs of concept are not verified: some are fake or contain malware. Never run them outside an isolated lab.
Affected technologies (1)
CWEs
- NVD-CWE-Other
References
Show 12 references
- http://php.net/ChangeLog-5.php
- http://www.debian.org/security/2015/dsa-3358
- http://www.securityfocus.com/bid/76734
- http://www.securitytracker.com/id/1033548
- https://bugs.php.net/bug.php?id=70219
- https://security.gentoo.org/glsa/201606-10
- http://php.net/ChangeLog-5.php
- http://www.debian.org/security/2015/dsa-3358
- http://www.securityfocus.com/bid/76734
- http://www.securitytracker.com/id/1033548
- https://bugs.php.net/bug.php?id=70219
- https://security.gentoo.org/glsa/201606-10
Raw JSON (NVD)
Show
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"evaluatorComment": "<a href=\"http://cwe.mitre.org/data/definitions/416.html\">CWE-416: Use After Free</a>",
"sourceIdentifier": "security@opentext.com"
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