Vulnerability Monitor

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CVE-2016-4538


The bcpowmod function in ext/bcmath/bcmath.c in PHP before 5.5.35, 5.6.x before 5.6.21, and 7.x before 7.0.6 modifies certain data structures without considering whether they are copies of the _zero_, _one_, or _two_ global variable, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted call.


Security Impact Summary

This vulnerability carries a CRITICAL severity rating with a CVSS v3.1 score of 9.8, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 3 products from php, from fedoraproject, from opensuse organizations running these solutions should prioritize assessment and patching.

Historical Context

First disclosed in 2016, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.


Published

2016-05-22T01:59:22.933

Last Modified

2025-04-12T10:46:40.837

Status

Deferred

Source

[email protected]

Severity

CVSSv3.0: 9.8 (CRITICAL)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:P/I:P/A:P

  • Access Vector: NETWORK
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: PARTIAL
  • Integrity Impact: PARTIAL
  • Availability Impact: PARTIAL
Exploitability Score

10.0

Impact Score

6.4

Weaknesses
  • Type: Primary
    CWE-20

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application php php ≤ 5.5.33 Yes
Application php php 5.6.0 Yes
Application php php 5.6.1 Yes
Application php php 5.6.2 Yes
Application php php 5.6.3 Yes
Application php php 5.6.4 Yes
Application php php 5.6.5 Yes
Application php php 5.6.6 Yes
Application php php 5.6.7 Yes
Application php php 5.6.8 Yes
Application php php 5.6.9 Yes
Application php php 5.6.10 Yes
Application php php 5.6.11 Yes
Application php php 5.6.12 Yes
Application php php 5.6.13 Yes
Application php php 5.6.14 Yes
Application php php 5.6.15 Yes
Application php php 5.6.16 Yes
Application php php 5.6.17 Yes
Application php php 5.6.18 Yes
Application php php 5.6.19 Yes
Application php php 5.6.20 Yes
Application php php 7.0.0 Yes
Application php php 7.0.1 Yes
Application php php 7.0.2 Yes
Application php php 7.0.3 Yes
Application php php 7.0.4 Yes
Application php php 7.0.5 Yes
Operating System fedoraproject fedora 24 Yes
Operating System opensuse leap 42.1 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For php's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.