CVE-2015-6835
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Last Modified:
Description
A flaw was discovered in the way PHP performed object unserialization. Specially crafted input processed by the unserialize() function could cause a PHP application to crash or, possibly, execute arbitrary code.
Additional information
- Bugzilla 1260647: php: use-after-free vulnerability in session deserializer
- CWE-416: Use After Free
- FAQ: Frequently asked questions about CVE-2015-6835
Common Vulnerability Scoring System (CVSS) Score Details
Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
| Red Hat | NVD | |
|---|---|---|
CVSS v2 Base Score | 5.1 | 7.5 |
Attack Vector | Network | Network |
Access Complexity | High | Low |
Authentication | None | None |
Confidentiality Impact | Partial | Partial |
Integrity Impact | Partial | Partial |
Availability Impact | Partial | Partial |
CVSS v2 Vector
Red Hat: AV:N/AC:H/Au:N/C:P/I:P/A:P
NVD: AV:N/AC:L/Au:N/C:P/I:P/A:P
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
Frequently Asked Questions
Why is Red Hat's CVSS v3 score or Impact different from other vendors?
My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
What can I do if my product is listed as "Will not fix"?
What can I do if my product is listed as "Fix deferred"?
What is a mitigation?
I have a Red Hat product but it is not in the above list, is it affected?
Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?
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