CVE-2016-1840

CVE-2016-1840 is a high-severity vulnerability in Apple Iphone Os with a CVSS 3.x base score of 7.8. 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-119.

Key facts

• Severity: High (CVSS 3.x base score 7.8)
• CVSS v2: 6.8
• EPSS exploit prediction: 3% (88th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-119
• Affected product: Apple Iphone Os
• Published: 2016-05-20
• Last modified: 2026-06-17

Description

Heap-based buffer overflow in the xmlFAParsePosCharGroup function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted XML document.

Frequently asked questions

What is CVE-2016-1840?

Heap-based buffer overflow in the xmlFAParsePosCharGroup function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted XML document.

How severe is CVE-2016-1840?

CVE-2016-1840 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-1840 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-1840?

CVE-2016-1840 primarily affects Apple Iphone Os. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-1840?

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

When was CVE-2016-1840 published?

CVE-2016-1840 was published on 2016-05-20 and last updated on 2026-06-17.

References

• http://lists.apple.com/archives/security-announce/2016/May/msg00001.html
• http://lists.apple.com/archives/security-announce/2016/May/msg00002.html
• http://lists.apple.com/archives/security-announce/2016/May/msg00003.html
• http://lists.apple.com/archives/security-announce/2016/May/msg00004.html
• http://rhn.redhat.com/errata/RHSA-2016-2957.html
• http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
• http://www.oracle.com/technetwork/topics/security/linuxbulletinjul2016-3090544.html
• http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
• http://www.securityfocus.com/bid/90691
• http://www.securitytracker.com/id/1035890
• http://www.ubuntu.com/usn/USN-2994-1
• http://xmlsoft.org/news.html
• https://access.redhat.com/errata/RHSA-2016:1292
• https://bugzilla.gnome.org/show_bug.cgi?id=757711
• https://git.gnome.org/browse/libxml2/commit/?id=cbb271655cadeb8dbb258a64701d9a3a0c4835b4
• https://kc.mcafee.com/corporate/index?page=content&id=SB10170
• https://security.gentoo.org/glsa/201701-37
• https://support.apple.com/HT206564
• https://support.apple.com/HT206566
• https://support.apple.com/HT206567
• https://support.apple.com/HT206568
• https://www.debian.org/security/2016/dsa-3593
• https://www.tenable.com/security/tns-2016-18

Affected products (29)

• cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
• cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*
• cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:*
• cpe:2.3:o:apple:watchos:*:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_desktop:6.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server:6.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_aus:7.2:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_aus:7.3:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_aus:7.4:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_aus:7.6:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_eus:7.2:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_eus:7.3:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_eus:7.4:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_eus:7.5:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_eus:7.6:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_tus:7.2:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_tus:7.3:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_tus:7.6:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_workstation:6.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*
• cpe:2.3:a:xmlsoft:libxml2:*:*:*:*:*:*:*:*
• cpe:2.3:a:mcafee:web_gateway:*:*:*:*:*:*:*:*

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