How severe is CVE-2016-6290?

CVE-2016-6290 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-6290 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6290?

CVE-2016-6290 primarily affects Php. In total, 40 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6290?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2016-6290 published?

CVE-2016-6290 was published on 2016-07-25 and last updated on 2026-06-17.

CVE-2016-6290

CVE-2016-6290 is a critical-severity vulnerability in Php with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 5% (92nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Php
Published: 2016-07-25
Last modified: 2026-06-17

Description

ext/session/session.c in PHP before 5.5.38, 5.6.x before 5.6.24, and 7.x before 7.0.9 does not properly maintain a certain hash data structure, which allows remote attackers to cause a denial of service (use-after-free) or possibly have unspecified other impact via vectors related to session deserialization.

Frequently asked questions

What is CVE-2016-6290?: ext/session/session.c in PHP before 5.5.38, 5.6.x before 5.6.24, and 7.x before 7.0.9 does not properly maintain a certain hash data structure, which allows remote attackers to cause a denial of service (use-after-free) or possibly have unspecified other impact via vectors related to session deserialization.
How severe is CVE-2016-6290?: CVE-2016-6290 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-6290 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6290?: CVE-2016-6290 primarily affects Php. In total, 40 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6290?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2016-6290 published?: CVE-2016-6290 was published on 2016-07-25 and last updated on 2026-06-17.

References

Affected products (40)

cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:alpha1:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:alpha2:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:alpha3:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:alpha4:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:alpha5:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:beta1:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:beta2:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:beta3:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:beta4:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.1:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.2:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.3:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.4:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.5:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.6:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.7:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.8:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.9:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.10:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.11:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.12:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.13:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.14:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.15:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.16:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.17:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.18:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.19:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.20:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.21:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.22:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.23:*:*:*:*:*:*:*
cpe:2.3:a:php:php:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:php:php:7.0.1:*:*:*:*:*:*:*
cpe:2.3:a:php:php:7.0.2:*:*:*:*:*:*:*
cpe:2.3:a:php:php:7.0.3:*:*:*:*:*:*:*
cpe:2.3:a:php:php:7.0.4:*:*:*:*:*:*:*
cpe:2.3:a:php:php:7.0.5:*:*:*:*:*:*:*
cpe:2.3:a:php:php:7.0.8:*:*:*:*:*:*:*

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Other CWE-416 (Use After Free) vulnerabilities

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CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
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Browse all CWE-416 (Use After Free) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

45.84.120.3 (ipv4-addr)
79.137.34.248 (ipv4-addr)
221.161.235.168 (ipv4-addr)
200.196.50.91 (ipv4-addr)
187.51.208.158 (ipv4-addr)
187.141.71.166 (ipv4-addr)
187.110.238.50 (ipv4-addr)
116.255.252.44 (ipv4-addr)