Cisco VPN 3000 series concentrators before 2.5.2(F) allow remote attackers to cause a denial of service via a flood of invalid login request
Cisco VPN 3000 series concentrators before 2.5.2(F) allow remote attackers to cause a denial of service via a flood of invalid login requests to (1) the SSL service, or (2) the telnet service, which do not properly disconnect the user after several failed login attempts.
- Published
- Jun 18, 2001
- Updated
- Jun 16, 2026
- EPSS
- 2.5% · 84th percentile
- CWE
- CWE-20
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Report tools
Action score
29
Monitor
Low priority for now.
- CVSS
- 28 / 40 · 7.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.5%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| cisco | vpn 3000 concentrator | cpe:2.3:h:cisco:vpn_3000_concentrator |
| cisco | vpn 3005 concentrator | cpe:2.3:h:cisco:vpn_3005_concentrator |
| cisco | vpn 3015 concentrator | cpe:2.3:h:cisco:vpn_3015_concentrator |
| cisco | vpn 3030 concentator | cpe:2.3:h:cisco:vpn_3030_concentator |
| cisco | vpn 3060 concentrator | cpe:2.3:h:cisco:vpn_3060_concentrator |
| cisco | vpn 3080 concentrator | cpe:2.3:h:cisco:vpn_3080_concentrator |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- cisco vpn 3000 concentratorall versions
- cisco vpn 3005 concentratorall versions
- cisco vpn 3015 concentratorall versions
- cisco vpn 3030 concentatorall versions
- cisco vpn 3060 concentratorall versions
- cisco vpn 3080 concentratorall versions
Same product
cisco: all recordsOther highest-scoring records for the same primary product.
- CVE-2005-2025Cisco VPN 3000 Concentrator before 4.1.7.F allows remote attackers to determine valid groupnames by sending an IKE Aggressive Mode packet wi21Monitor
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
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
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.
No dated events beyond publication.
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
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- C · the service can be disrupted
- Attack complexity
- M
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- C
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
AV:N/AC:M/Au:N/C:N/I:N/A:C
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.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
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.cisco.com/warp/public/707/vpn3k-telnet-vuln-pub.shtml
- www.osvdb.org/5643
- exchange.xforce.ibmcloud.com/vulnerabilities/6298
Vendor advisories and official records. Exploit/PoC links are deliberately left out.