What is CVE-2016-5399?

CVE-2016-5399 is a high-severity vulnerability in PHP, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2017-04-21.

How severe is CVE-2016-5399?

High severity. CVSS v3 base score is 7.8 out of 10.

Is CVE-2016-5399 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in PHP

CVE-2016-5399

The bzread function in ext/bz2/bz2.c in PHP before 5.5.38, 5.6.x before 5.6.24, and 7.x before 7.0.9 allows remote attackers to cause a denial of service (out-of-bounds write) or execute arbitrary code via a crafted bz2 archive.

Vulnerability class: Buffer Overflow

Published 2017-04-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.098 (95.4th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 95th percentile — 95.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.098 · newest: 0.098 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

Public proof-of-concept exploits

References

www.securityfocus.com/bid/92051 (VDB Entry, Third Party Advisory, vdb-entry)
packetstormsecurity.com/files/137998/PHP-7.0.8-5.6.23-5.5.37-bzread-OOB-Write.h… (Exploit, VDB Entry, Third Party Advisory)
seclists.org/fulldisclosure/2016/Jul/72 (mailing-list, Exploit, Mailing List, Third Party Advisory)
bugzilla.redhat.com/show_bug.cgi (VDB Entry, Third Party Advisory, Issue Tracking)
www.openwall.com/lists/oss-security/2016/07/21/1 (mailing-list, Exploit, Mailing List, Third Party Advisory)
www.securityfocus.com/archive/1/538966/100/0/threaded (mailing-list, VDB Entry, Third Party Advisory)
bugs.php.net/bug.php (Exploit, Vendor Advisory)
rhn.redhat.com/errata/RHSA-2016-2750.html (vendor-advisory, Third Party Advisory)
rhn.redhat.com/errata/RHSA-2016-2598.html (vendor-advisory, Third Party Advisory)
php.net/ChangeLog-5.php (Release Notes, Vendor Advisory)

Frequently asked questions

What is CVE-2016-5399?: CVE-2016-5399 is a high-severity vulnerability in PHP, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2017-04-21.
How severe is CVE-2016-5399?: High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2016-5399 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.