Cisco Adaptive Security Appliance (ASA) Denial-of-Service Vulnerability
Exploited since 2021-11-03. 1 of 8 rule sources name it. Our CRS test: blocked.
A vulnerability in the web interface of the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. It is… More
A vulnerability in the web interface of the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. It is also possible on certain software releases that the ASA will not reload, but an attacker could view sensitive system information without authentication by using directory traversal techniques. The vulnerability is due to lack of proper input validation of the HTTP URL. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. An exploit could allow the attacker to cause a DoS condition or unauthenticated disclosure of information. This vulnerability applies to IPv4 and IPv6 HTTP traffic. This vulnerability affects Cisco ASA Software and Cisco Firepower Threat Defense (FTD) Software that is running on the following Cisco products: 3000 Series Industrial Security Appliance (ISA), ASA 1000V Cloud Firewall, ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, Adaptive Security Virtual Appliance (ASAv), Firepower 2100 Series Security Appliance, Firepower 4100 Series Security Appliance, Firepower 9300 ASA Security Module, FTD Virtual (FTDv). Cisco Bug IDs: CSCvi16029.
Edge coverage
Claimed by vendorsAsk Vigil
AI · answers from this pageWorkers AI (Llama 3.3). Can be wrong: check the cited source.
Severity, decoded
CVSS 3.1Exploitable over the network, with no privileges and no user interaction, leading to full loss of availability.
How the score is built
- Attack vectorAn attacker can reach it over the internet; no access to your network needed.Network
- Attack complexityNo special conditions are needed; the attack works reliably.Low
- Privileges requiredNo account or login is needed.None
- User interactionNo one has to click or open anything; the attack works on its own.None
- ScopeThe damage stays within the vulnerable component.Unchanged
- Confidentiality impactNo data is exposed.None
- Integrity impactData cannot be changed by the attacker.None
- Availability impactAn attacker can take the component down completely or keep it from serving anyone.High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HAttackers are exploiting this in the wild.
Attackers can script the attack end to end and hit many targets at once.
A successful attack gives limited control over the affected software or limited access to its data.
Public exploits
4 found- MetasploitCisco ASA Directory Traversal2018-06-06 · auxiliary · rank Normal
- Exploit-DBCisco Adaptive Security Appliance - Path Traversal (Metasploit)2019-08-12 · webapps · hardware
- Exploit-DBCisco Adaptive Security Appliance - Path Traversal2018-06-28 · webapps · hardware
- NucleiCVE-2018-0296.yamldetection template, replayed in our lab
Links are to third-party code: never run it outside an isolated lab.
Timeline
- 2018-06-06Metasploit module publishedCisco ASA Directory Traversal
- 2018-06-07CVE publishedCVE List
- 2018-06-28Exploit published on Exploit-DBCisco Adaptive Security Appliance - Path Traversal
- 2021-11-03Added to CISA KEVConfirmed exploitation in the wild
- 2025-12-03F5 rule names itEarliest entry we can see is an update
- 2026-11-02Our test: OWASP Core Rule Set blocked itparanoia level 1, anomaly threshold 5, default CRS settings
- 2026-11-02Our test: OWASP Core Rule Set blocked itparanoia level 2, anomaly threshold 5, default CRS settings
Vendor statements
QuotedCloudflareWAF Managed Rules
The CVE predates the oldest entry in this vendor's public feed, so a rule may exist that we cannot see.
AWSAWS WAF Managed Rules
The CVE predates the oldest entry in this vendor's public feed, so a rule may exist that we cannot see.
Microsoft AzureFront Door and Application Gateway WAF (DRS)
We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. The rule tables name CVEs but carry no dates, so Azure is left out of every time-to-rule figure.
Google CloudCloud Armor preconfigured WAF rules
The CVE predates the oldest entry in this vendor's public feed, so a rule may exist that we cannot see.
FastlyNext-Gen WAF virtual patches
The CVE predates the oldest entry in this vendor's public feed, so a rule may exist that we cannot see.
F5Attack signatures (Distributed Cloud WAF)
Named by 2025-12-03; the first entry is an update, so the rule may be older.
Updated: signature 200013049 "Cisco ASA authorization bypass" (Authentication/Authorization Attacks, risk High), systems: Cisco. References: CVE-2025-20362, CVE-2018-0296.
AkamaiApp & API Protector (Adaptive Security Engine)
This vendor publishes no machine-readable rule changelog we can check.
OWASP CRSCore Rule Set (open source, used inside many WAFs)
The CVE predates the oldest entry in this vendor's public feed, so a rule may exist that we cannot see.
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