CVE-2001-0537
CriticalExploitedPublic exploitHTTP server for Cisco IOS 11.3 to 12.2 allows attackers to bypass authentication and execute arbitrary commands, when local authorization is being used, by specifying a high access level in the URL.
Published Jul 21, 2001 · Updated Apr 15, 2026
Key Facts
Patch immediately- CVE-2001-0537 is a critical-severity vulnerability (CVSS 9.3 v2) affecting IOS (Cisco).
- It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Oct 14, 2023. Public exploit code is available.
- EPSS estimates a 68% 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 it is listed as exploited in the wild.
CVSS v2
9.3
AV:N/AC:M/Au:N/C:C/I:C/A:C
EPSS (30-day exploit likelihood)
68%
Higher than 99.3% of all scored CVEs
Exploited in the wild
Yes
2 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
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Description
HTTP server for Cisco IOS 11.3 to 12.2 allows attackers to bypass authentication and execute arbitrary commands, when local authorization is being used, by specifying a high access level in the URL.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Nov 15, 2023 | n/a | Not reported |
| CIRCL KEV | Oct 14, 2023 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
91 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| IOSCisco | 11.3, 11.3aa, 11.3da, 11.3db, 11.3ha, 11.3ma, 11.3na, 11.3t | n/a |
Timeline
Publicly disclosed
Jul 21, 2001
Added to CIRCL KEV
Oct 14, 2023
Added to Industry KEV feed
Nov 15, 2023
Last updated
Apr 15, 2026
Weakness Type
- CWE-287 Improper Authentication
References
- patchCA-2001-14
- patch20010627 IOS HTTP authorization vulnerability
- patch2936
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
HTTP server for Cisco IOS 11.3 to 12.2 allows attackers to bypass authentication and execute arbitrary commands, when local authorization is being used, by specifying a high access level in the URL.
Affected: IOS (Cisco) versions 11.3, 11.3aa, 11.3da, 11.3db, 11.3ha, 11.3ma, 11.3na, 11.3t. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Oct 14, 2023.
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 it is listed as exploited in the wild.
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