CVE-2013-0340 — expat 2.1.0 and earlier does not properly handle entities expansion unless an application...
expat before version 2.4.0 does not properly handle entities expansion unless an application developer uses the XML_SetEntityDeclHandler function, which allows remote attackers to cause a denial of service (resource consumption), send HTTP requests to intranet servers, or read arbitrary files via a crafted XML document, aka an XML External Entity (XXE) issue. NOTE: it could be argued that because expat already provides the ability to disable external entity expansion, the responsibility for resolving this issue lies with application developers; according to this argument, this entry should be REJECTed, and each affected application would need its own CVE.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 19.4% (30-day exploitation probability)+15
- Technical severity (medium)+3
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
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.
- Identify exposed assets running the affected vendor/product/version combinations (Apple Ipados, Apple Iphone Os, Apple Macos…).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- EPSS ahead of 97% of scored CVEs: prioritize it in the patch queue.
- Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Apple | Ipados | < 14.8 | Vulnerable | NIST National Vulnerability Database |
| Apple | Iphone Os | < 14.8 | Vulnerable | NIST National Vulnerability Database |
| Apple | Macos | < 11.6 | Vulnerable | NIST National Vulnerability Database |
| Apple | Tvos | < 15.0 | Vulnerable | NIST National Vulnerability Database |
| Apple | Watchos | < 8.0 | Vulnerable | NIST National Vulnerability Database |
| Libexpat Project | Libexpat | < 2.4.0 | Vulnerable | NIST National Vulnerability Database |
| Python | Python | ≥ 3.6.0 and < 3.6.15≥ 3.7.0 and < 3.7.12≥ 3.8.0 and < 3.8.12≥ 3.9.0 and < 3.9.7 | Vulnerable | NIST National Vulnerability Database |
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.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 6.8 | CVSS 2.0 | Medium | 8.6 | 6.4 | nvd@nist.gov via NIST National Vulnerability Database |
AV:N/AC:M/Au:N/C:P/I:P/A:P (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 19.43%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Look for parameters with command/query metacharacters and unexpected child processes of the service.
Timeline
What happened to this CVE, newest first.
- 2026
- SSVC assessment updated
- Record published
- CVSS changed · 6.8
- Source status changed · → Modified
- Record created in this database
- 2014
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
30 on the record
- seclists.org/fulldisclosure/2021/Sep/35
- github.com/libexpat/libexpat/blob/R_2_4_1/expat/Changes
- support.apple.com/kb/HT212807
- www.openwall.com/lists/oss-security/2021/10/07/4
- github.com/advisories/GHSA-w3v2-46wf-pq33
- support.apple.com/kb/HT212815
- support.apple.com/kb/HT212819
- seclists.org/fulldisclosure/2021/Sep/38
- seclists.org/fulldisclosure/2021/Oct/62
- seclists.org/fulldisclosure/2021/Oct/61
- support.apple.com/kb/HT212805
- support.apple.com/kb/HT212814
- seclists.org/fulldisclosure/2021/Sep/39
- lists.apache.org/thread.html/rfb2c193360436e230b85547e85a41bea0916916f96c501f5b6fc4702
- nvd.nist.gov/vuln/detail/CVE-2013-0340
- support.apple.com/kb/HT212804
- openwall.com/lists/oss-security/2013/02/22/3
- security.gentoo.org/glsa/201701-21
- lists.apache.org/thread.html/rfb2c193360436e230b85547e85a41bea0916916f96c501f5b6fc4702
- lists.apache.org/thread.html/r41eca5f4f09e74436cbb05dec450fc2bef37b5d3e966aa7cc5fada6d
- seclists.org/fulldisclosure/2021/Sep/40
- www.osvdb.org/90634
- seclists.org/fulldisclosure/2021/Oct/63
- cert-portal.siemens.com/productcert/html/ssa-398330.html
- seclists.org/fulldisclosure/2021/Sep/33
- www.openwall.com/lists/oss-security/2013/04/12/6
- seclists.org/fulldisclosure/2021/Sep/34
- lists.apache.org/thread.html/r41eca5f4f09e74436cbb05dec450fc2bef37b5d3e966aa7cc5fada6d
- www.securityfocus.com/bid/58233
- securitytracker.com/id
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-86950 Apple Multiple Products Out-of-Bounds Write Vulnerability KEV 17d
- Medium CVE-2026-86903 Out-of-bounds Read in Apple Ipados Sep 14, 2026
- Medium CVE-2026-86924 Improper Input Validation in Apple Ipados Sep 14, 2026
- Medium CVE-2026-86905 Improper Access Control 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-2026-86911 Clickjacking in Apple Macos 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 fixed version, patch or mitigation documented.
- 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-2013-0340 is "expat 2.1.0 and earlier does not properly handle entities expansion unless an application...", rated Medium. It affects Ipados (Apple); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.8 describes technical severity. EPSS 19.43% 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.
Comments
Moderated technical discussion. Read the community guidelines.
No comments yet.
Sign in or create an account to comment and suggest corrections.