High [CVE-2026-20125] Cisco IOS Software and IOS XE Software Release 3E HTTP Server Denial of Service Vulnerability
This high-severity Cisco advisory covers CVE-2026-20125 affecting Cisco IOS 12.2(33)CY1, Cisco IOS 12.2(33)CY2, Cisco IOS 12.2(55)SE3.
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Summary
A vulnerability in the HTTP Server feature of Cisco IOS Software and Cisco IOS XE Software Release 3E could allow an authenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper validation of user-supplied input.
An attacker could exploit this vulnerability by sending malformed HTTP requests to an affected device. A successful exploit could allow the attacker to cause a watchdog timer to expire and the device to reload, resulting in a DoS condition.
Affected products named by the advisory: Cisco IOS 12.2(33)CY1; Cisco IOS 12.2(33)CY2; Cisco IOS 12.2(55)SE3; Cisco IOS 12.2(55)SE2; and 2 more.
- Scope: This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco IOS Software or IOS XE Software Release 3E and they have the HTTP Server feature enabled with an active WEB_EXEC module.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- There are no workarounds that address this vulnerability.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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