IIS 4.0 and 5.0 does not properly perform ISAPI extension processing if a virtual directory is mapped to a UNC share, which allows remote at
IIS 4.0 and 5.0 does not properly perform ISAPI extension processing if a virtual directory is mapped to a UNC share, which allows remote attackers to read the source code of ASP and other files, aka the "Virtualized UNC Share" vulnerability.
- Published
- Mar 30, 2000
- Updated
- Jun 16, 2026
- EPSS
- 80.0% · 100th percentile
- CWE
- —
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Report tools
Action score
44
Plan
Add it to your regular patch cycle.
- CVSS
- 20 / 40 · 5.0 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 24 / 30 · 80.0%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| microsoft | commercial internet system | cpe:2.3:a:microsoft:commercial_internet_system |
| microsoft | internet information server | cpe:2.3:a:microsoft:internet_information_server |
| microsoft | internet information services | cpe:2.3:a:microsoft:internet_information_services |
| microsoft | proxy server | cpe:2.3:a:microsoft:proxy_server |
| microsoft | site server | cpe:2.3:a:microsoft:site_server |
| microsoft | site server commerce | cpe:2.3:a:microsoft:site_server_commerce |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- microsoft commercial internet system2.0
- microsoft commercial internet system2.5
- microsoft internet information server4.0
- microsoft internet information services5.0
- microsoft proxy server2.0
- microsoft site server3.0
- microsoft site server commerce3.0
Same product
microsoft: all recordsOther highest-scoring records for the same primary product.
- CVE-2000-0053Microsoft Commercial Internet System (MCIS) IMAP server allows remote attackers to cause a denial of service via a malformed IMAP request.34Monitor
- CVE-1999-0777IIS FTP servers may allow a remote attacker to read or delete files on the server, even if they have "No Access" permissions.34Monitor
- CVE-1999-0867Denial of service in IIS 4.0 via a flood of HTTP requests with malformed headers.26Monitor
- CVE-1999-0910Microsoft Site Server and Commercial Internet System (MCIS) do not set an expiration for a cookie, which could then be cached by a proxy and22Monitor
- CVE-1999-0861Race condition in the SSL ISAPI filter in IIS and other servers may leak information in plaintext.11Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Exploit-DB entry ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Exploit-DB entry | remote | 2000-03-30 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- First PoCsame day
- Published
- TodaySep 30, 2026+9680 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- P · data can be read
- Integrity
- none
- Availability
- none
- Attack complexity
- Low
- Confidentiality impact
- P
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
—
CVSS vector
AV:N/AC:L/Au:N/C:P/I:N/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- www.microsoft.com/technet/support/kb.asp?ID=249599
- www.securityfocus.com/bid/1081
- docs.microsoft.com/en-us/security-updates/securitybulletins/2000/ms00-019
Vendor advisories and official records. Exploit/PoC links are deliberately left out.