Microsoft Internet Explorer 10 and 11 load different files for attempts to open a file:// URL depending on whether the file exists, which allows local users to enumerate files via vectors involving a file:// URL and an HTML5 sandbox iframe, aka "Internet Explorer Information Disclosure Vulnerability."
CVE-2016-3321
Score elevated to 3.1 because EPSS predicts 35% probability of exploitation within the next 30 days (top 1.7% of all CVEs). NVD baseline CVSS 2.5 retained for reference. Confidence: see factors.
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 2.5
- EG Score
- 3.1(high)
- EG Risk
- 44(Track)EG Risk 44/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity31% × 45%Exploitation65% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 98.3%
- KEV
- Not listed
Published
August 9, 2016
Last Modified
May 6, 2026
References (12)
- secure@microsofthttp://seclists.org/fulldisclosure/2016/Aug/44
- secure@microsofthttp://www.securityfocus.com/archive/1/539174/100/0/threaded
- secure@microsofthttp://www.securityfocus.com/bid/92291
- secure@microsofthttp://www.securitytracker.com/id/1036562
- secure@microsofthttps://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-095
- secure@microsofthttps://www.securify.nl/advisory/SFY20160301/internet_explorer_iframe_sandbox_local_file_name_disclosure_vulnerability.html
- af854a3a-2127-422b-91ae-364da2661108http://seclists.org/fulldisclosure/2016/Aug/44
- af854a3a-2127-422b-91ae-364da2661108http://www.securityfocus.com/archive/1/539174/100/0/threaded
- af854a3a-2127-422b-91ae-364da2661108http://www.securityfocus.com/bid/92291
- af854a3a-2127-422b-91ae-364da2661108http://www.securitytracker.com/id/1036562
- af854a3a-2127-422b-91ae-364da2661108https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-095
- af854a3a-2127-422b-91ae-364da2661108https://www.securify.nl/advisory/SFY20160301/internet_explorer_iframe_sandbox_local_file_name_disclosure_vulnerability.html
Data Freshness Timeline
(refreshed 10× in last 7d / 30× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 14:14 UTCEPSS rescore
- 2026-07-23 01:22 UTCEG score recompute▲ 0.60
- 2026-07-22 22:02 UTCEG score recompute
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- 2026-06-30 23:19 UTCEPSS rescore
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- 2026-05-22 21:15 UTCEPSS rescore
- 2026-05-22 21:15 UTCEPSS rescore
- 2026-05-22 19:03 UTCEG score recompute
- 2026-05-22 19:02 UTCGHSA enrichment
- 2026-05-21 22:40 UTCEPSS rescore
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- 2026-05-18 21:30 UTCEPSS rescore
- 2026-05-18 21:30 UTCEPSS rescore
Publicly available exploits
(1 reference)Working exploit code is in the public domain (1 Metasploit module). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.
- Metasploitauxiliary/gather/ie_sandbox_findfiles✓ verifiedFirst seen Aug 9, 2016
Internet Explorer Iframe Sandbox File Name Disclosure Vulnerability
Open source ↗
Frequently asked(5)
What is CVE-2016-3321?
When was CVE-2016-3321 disclosed?
Is CVE-2016-3321 actively exploited?
What is the CVSS score of CVE-2016-3321?
How do I remediate CVE-2016-3321?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2016-3321
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