CVE-2016-5768

CVE-2016-5768 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-415.

Key facts

• Severity: Critical (CVSS 3.x base score 9.8)
• CVSS v2: 7.5
• EPSS exploit prediction: 10% (95th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-415
• Affected product: Php
• Published: 2016-08-07
• Last modified: 2026-06-17

Description

Double free vulnerability in the _php_mb_regex_ereg_replace_exec function in php_mbregex.c in the mbstring extension in PHP before 5.5.37, 5.6.x before 5.6.23, and 7.x before 7.0.8 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) by leveraging a callback exception.

Frequently asked questions

What is CVE-2016-5768?

Double free vulnerability in the _php_mb_regex_ereg_replace_exec function in php_mbregex.c in the mbstring extension in PHP before 5.5.37, 5.6.x before 5.6.23, and 7.x before 7.0.8 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) by leveraging a callback exception.

How severe is CVE-2016-5768?

CVE-2016-5768 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-2016-5768 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-5768?

CVE-2016-5768 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-2016-5768?

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-2016-5768 published?

CVE-2016-5768 was published on 2016-08-07 and last updated on 2026-06-17.

References

• http://github.com/php/php-src/commit/5b597a2e5b28e2d5a52fc1be13f425f08f47cb62?w=1
• http://lists.apple.com/archives/security-announce/2016/Sep/msg00006.html
• http://lists.opensuse.org/opensuse-security-announce/2016-07/msg00004.html
• http://lists.opensuse.org/opensuse-updates/2016-08/msg00003.html
• http://php.net/ChangeLog-5.php
• http://php.net/ChangeLog-7.php
• http://rhn.redhat.com/errata/RHSA-2016-2598.html
• http://rhn.redhat.com/errata/RHSA-2016-2750.html
• http://www.debian.org/security/2016/dsa-3618
• http://www.openwall.com/lists/oss-security/2016/06/23/4
• http://www.securityfocus.com/bid/91396
• https://bugs.php.net/bug.php?id=72402
• https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05240731
• https://support.apple.com/HT207170

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: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:7.0.6:*:*:*:*:*:*:*
• cpe:2.3:a:php:php:7.0.7:*:*:*:*:*:*:*

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All CVEs affecting Php →

Other CWE-415 (Double Free) vulnerabilities

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• CVE-2026-8925 — Critical (CVSS 9.8): The curl logic that works with SASL authentication could end up cleaning up the GSASL context *twice* without clearing…
• CVE-2020-37239 — Critical (CVSS 9.8): libbabl 0.1.62 contains a broken double free detection vulnerability that allows attackers to bypass memory safety…
• CVE-2026-43011 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: net/x25: Fix potential double free of skb When…
• CVE-2026-31609 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: avoid double-free in…
• CVE-2026-31608 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: server: avoid double-free in…

Browse all CWE-415 (Double 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)