Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 1.66% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2016
CVE-2016-4449High confidence
Affected product: Improper Input Validation
Unknown · Unknown
7.1HighCVSS 3.0
Within 7 days
Mitigation availableHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
4 package statesRelease-specific package status
Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | libxml2 | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.3+dfsg1-1.1 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian bookwormbookworm · source | libxml2 | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.3+dfsg1-1.1 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian forkyforky · source | libxml2 | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.3+dfsg1-1.1 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian sidsid · source | libxml2 | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.3+dfsg1-1.1 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
Direct vendor intelligence
0 current · 1 archivedAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2016-4449 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitylibxml2: Inappropriate fetch of entities contentNo longer in the provider’s current catalogue
The vendor explicitly identifies these products as affected by this CVE.
- libxml2.src as a component of Red Hat Enterprise Linux 5
- libxml2.src as a component of Red Hat JBoss Enterprise Web Server 3
- Summary
- XML external entity (XXE) vulnerability in the xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.4, when not in validating mode, allows context-dependent attackers to read arbitrary files or cause a denial of service (resource consumption) via unspecified vectors.
- Remediation
- For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 For the update to take effect, all applications linked to the libxml2 library must be restarted, or the system rebooted.
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Mitigation available01
What, why and how
XML external entity (XXE) vulnerability in the xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.4, when not in validating mode, allows context-dependent attackers to read arbitrary files or cause a denial of service (resource consumption) via unspecified vectors.
What
XML external entity (XXE) vulnerability in the xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.4, when not in validating mode, allows context-dependent attackers to read arbitrary files or cause a denial of service (resource consumption) via unspecified vectors.
Why
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
How
An attacker operating through local access may attempt exploitation without authentication after a user interaction. If successful, the issue may obtain information outside the intended access boundary.
What
XML external entity (XXE) vulnerability in the xmlStringLenDecodeEntities function in parser.c in libxml2 before 2.9.4, when not in validating mode, allows context-dependent attackers to read arbitrary files or cause a denial of service (resource consumption) via unspecified vectors.
Why
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
How
An attacker operating through local access may attempt exploitation without authentication after a user interaction. If successful, the issue may obtain information outside the intended access boundary.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- local access → Improper Input Validation → obtain information outside the intended access boundary
- Attack surface
- Local
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Required interaction required
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-20 ↗
CWE-20: Improper Input Validation. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:HCommon Vulnerability Scoring System 3.0: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Mitigation available
- Affected
- n/a
- Action
- CCIRC recommends that system administrators identify their affected assets and potential interdependencies with their organization’s critical services, and follow their patch management process accordingly. References: http://www.oracle.com/technetwork/security-advisory/cpujan2018-3236628.html
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
Official vendor articles6 stored documents
Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.
- About the security content of iCloud for Windows 5.2.1 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of iTunes 12.4.2 for Windows - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of iOS 9.3.3 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of OS X El Capitan v10.11.6 and Security Update 2016-004 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of watchOS 2.2.2 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of tvOS 9.2.2 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
04
Evidence and provenance
Published 9 Jun 2016 · Last source change 6 Aug 2024, 00:32 UTC · CWE-20 · Improper Input Validation
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-09-01
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2016-5438
Product sourceUnavailable
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment
Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2016-4449 to advisory no longer present in the provider's current catalogue.Red Hat Product Security ↗
- Before
- remediation: access.redhat.com/CVE-2016-4449
- After
- advisory no longer present in the provider's current catalogue
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- n/a · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 For the update to take effect, all applications linked to the libxml2 library must be restarted, or the system rebooted.
- Remediation statusRemediation status changed from Mitigation available to Patch available.Red Hat Product Security ↗
- Before
- Mitigation available
- After
- Patch available
- ENISA EUVD mappingEUVD-2016-5438 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2016-5438"}
- Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: git.gnome.org/commit?id=b1d34de46a11323fccffa9fadeb33be670d602f5; removed vendor advisory: access.redhat.com/RHSA-2016:1292; removed vendor advisory: debian.org/dsa-3593; 8 further removals.git.gnome.org ↗
- Before
- vendor advisory: access.redhat.com/RHSA-2016:1292 · vendor advisory: debian.org/dsa-3593 · vendor advisory: lists.apple.com/msg00000.html · 7 more references
- After
- vendor advisory: git.gnome.org/commit?id=b1d34de46a11323fccffa9fadeb33be670d602f5
- SeveritySeverity changed from Unknown to High.NIST NVD ↗
- Before
- Unknown
- After
- High
- CVSS scoreCVSS score changed from not recorded to 7.1 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H).NIST NVD ↗
- Before
- not recorded
- After
- 7.1 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H)
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
- Remediation statusRemediation status changed from Patch available to Mitigation available.Canadian Centre for Cyber Security ↗
- Before
- Patch available
- After
- Mitigation available
- Remediation statusRemediation status changed from Awaiting fix to Mitigation available.Canadian Centre for Cyber Security ↗
- Before
- Awaiting fix
- After
- Mitigation available
CVE published
Remediation guidance recorded
Fixed release recorded from official guidance
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.