CVE-2000-0380IOS Vulnerability
The IOS HTTP service in Cisco routers and switches running IOS 11.1 through 12.1 allows remote attackers to cause a denial of service by requesting a URL that contains a %% string.
Published Apr 26, 2000 · Updated Apr 15, 2026
Key Facts
Patch immediately- CVE-2000-0380 is a high-severity vulnerability (CVSS 7.1 v2) affecting IOS (Cisco).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 35% probability of exploitation in the next 30 days.
- No fixed version is listed yet; check the vendor advisory for mitigations.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Scores
CVSS v2
7.1
AV:N/AC:M/Au:N/C:N/I:N/A:C
EPSS (30-day exploit likelihood)
35%
Higher than 98.4% of all scored CVEs
Exploit maturity
Proof of concept
ATLAS score
34/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Not listed
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Proof of concept
Public exploit code
1
Proof-of-concept links
In-the-wild evidence
0
Reports of active use
Description
The IOS HTTP service in Cisco routers and switches running IOS 11.1 through 12.1 allows remote attackers to cause a denial of service by requesting a URL that contains a %% string.
Affected Products
39 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| IOSCisco | 11.1, 11.2, 11.2\(10\), 11.2\(10\)bc, 11.2\(17\), 11.2\(4\)f1, 11.2\(8\), 11.2\(8\)p | n/a |
Timeline
Publicly disclosed
Apr 26, 2000
Last updated
Apr 15, 2026
Weakness Type
- CWE-20 Improper Input Validation
References
- exploitExploitDB-19882
- other20000426 Cisco HTTP possible bug:
- other20000514 Cisco IOS HTTP Server Vulnerability
- other1302
- other1154
FAQ
Common Questions.
The IOS HTTP service in Cisco routers and switches running IOS 11.1 through 12.1 allows remote attackers to cause a denial of service by requesting a URL that contains a %% string.
Affected: IOS (Cisco) versions 11.1, 11.2, 11.2\(10\), 11.2\(10\)bc, 11.2\(17\), 11.2\(4\)f1, 11.2\(8\), 11.2\(8\)p. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
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