CVE-2016-1839 — The xmlDictAddString function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X...

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

• Documented patch — git.gnome.org (NIST National Vulnerability Database)
• Documented patch — kc.mcafee.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Apple Iphone Os, Apple Mac Os X, Apple Tvos…).
2. Apply the fixed version or the patch documented under Remediation.
3. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
4. EPSS ahead of 94% of scored CVEs: prioritize it in the patch queue.
5. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-125 · Out-of-bounds Read

Other CVEs with this weakness →

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 7.35%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
• Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

Timeline

What happened to this CVE, newest first.

• 2026
• Record published
  Oct 14, 2026
• Fix documented
  Oct 14, 2026 · NIST National Vulnerability Database
• Affected products added · apple/iphone os, apple/mac os x, apple/tvos, apple/watchos, canonical/ubuntu linux, debian/debian linux, redhat/enterpri
  Oct 14, 2026 · NIST National Vulnerability Database
• CVSS changed · 5.5
  Oct 14, 2026 · NIST National Vulnerability Database
• Source status changed · → Modified
  Oct 14, 2026 · NIST National Vulnerability Database
• Record created in this database
  Oct 14, 2026 · Alertas do Telegram
• 2016
• CVE published
  May 20, 2016 · apple

Source activity

Repeated readings are counted rather than listed.

• 2× References added · Oct 14, 2026 – Oct 14, 2026
• 1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

26 on the record

• lists.apple.com/archives/security-announce/2016/May/msg00004.html
  Mailing List, Vendor Advisory, vendor-advisory, x_refsource_APPLE, NIST National Vulnerability Database
• support.apple.com/HT206566
  Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• lists.apple.com/archives/security-announce/2016/May/msg00003.html
  Mailing List, Vendor Advisory, vendor-advisory, x_refsource_APPLE, NIST National Vulnerability Database
• xmlsoft.org/news.html
  Release Notes, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• support.apple.com/HT206564
  Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• lists.apple.com/archives/security-announce/2016/May/msg00001.html
  Mailing List, Vendor Advisory, vendor-advisory, x_refsource_APPLE, NIST National Vulnerability Database
• lists.apple.com/archives/security-announce/2016/May/msg00002.html
  Mailing List, Vendor Advisory, vendor-advisory, x_refsource_APPLE, NIST National Vulnerability Database
• support.apple.com/HT206567
  Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• support.apple.com/HT206568
  Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• git.gnome.org/browse/libxml2/commit/
  Patch, Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• kc.mcafee.com/corporate/index
  Patch, Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• www.securityfocus.com/bid/90691
  Third Party Advisory, VDB Entry, vdb-entry, x_refsource_BID, NIST National Vulnerability Database
• access.redhat.com/errata/RHSA-2016:1292
  Third Party Advisory, vendor-advisory, x_refsource_REDHAT, NIST National Vulnerability Database
• www.debian.org/security/2016/dsa-3593
  Third Party Advisory, vendor-advisory, x_refsource_DEBIAN, NIST National Vulnerability Database
• www.securitytracker.com/id/1035890
  Third Party Advisory, VDB Entry, vdb-entry, x_refsource_SECTRACK, NIST National Vulnerability Database
• www.oracle.com/technetwork/topics/security/linuxbulletinjul2016-3090544.html
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• www.securitytracker.com/id/1038623
  Third Party Advisory, VDB Entry, vdb-entry, x_refsource_SECTRACK, NIST National Vulnerability Database
• www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• www.ubuntu.com/usn/USN-2994-1
  Third Party Advisory, vendor-advisory, x_refsource_UBUNTU, NIST National Vulnerability Database
• bugzilla.gnome.org/show_bug.cgi
  Exploit, Issue Tracking, Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• security.gentoo.org/glsa/201701-37
  Third Party Advisory, vendor-advisory, x_refsource_GENTOO, NIST National Vulnerability Database
• www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• github.com/advisories/GHSA-768p-297v-97cm
  GitHub Security Advisories
• nvd.nist.gov/vuln/detail/CVE-2016-1839
  GitHub Security Advisories
• rhn.redhat.com/errata/RHSA-2016-2957.html
  Third Party Advisory, vendor-advisory, x_refsource_REDHAT, NIST National Vulnerability Database
• www.tenable.com/security/tns-2016-18
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database

Elsewhere on this site

Related CVEs (same products)

• High CVE-2026-86950 Apple Multiple Products Out-of-Bounds Write Vulnerability KEV 17d
• Medium CVE-2026-86924 Improper Input Validation in Apple Ipados Sep 14, 2026
• High CVE-2026-86904 A privacy issue was addressed with improved state management. This issue is fixed in iOS… Sep 14, 2026
• Medium CVE-2026-86905 Improper Access Control in Apple Ipados Sep 14, 2026
• Medium CVE-2026-86903 Out-of-bounds Read in Apple Ipados Sep 14, 2026
• High CVE-2026-86895 Exposure of Sensitive Information in Apple Ipados Sep 14, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No CISA SSVC assessment.
• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2016-1839 is "The xmlDictAddString function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X...", rated Medium. It affects Iphone Os (Apple); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 7.35% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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