Cisco IOS 9.1 IP Access List privileges management

CVSS Meta Temp Score
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7.0$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Cisco IOS 9.1. Affected by this issue is some unknown functionality of the component IP Access List Handler. Such manipulation with the input established leads to privileges management. This vulnerability is uniquely identified as CVE-1999-1306. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco IOS 9.1 (Router Operating System). It has been rated as critical. Affected by this issue is some unknown functionality of the component IP Access List Handler. The manipulation with the input value established leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Cisco IOS 9.1 and earlier does not properly handle extended IP access lists when the IP route cache is enabled and the "established" keyword is set, which could allow attackers to bypass filters.

The weakness was disclosed 12/10/1992 as CERT CA-1992-20 as not defined advisory (CERT.org). The advisory is shared for download at cert.org. This vulnerability is handled as CVE-1999-1306. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1068.

The commercial vulnerability scanner Qualys is able to test this issue with plugin 43079 (Cisco IOS "Established" Keyword ACL Bypass Vulnerability).

Upgrading to version 8.3, 9.0 or 9.1 eliminates this vulnerability. It is possible to mitigate the problem by applying the configuration setting no ip route-cache. The best possible mitigation is suggested to be upgrading to the latest version. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Vulnerability Center (SBV-2058†). The entry VDB-13653 is pretty similar. Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Privileges management
CWE: CWE-269 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: IOS 8.3/9.0/9.1
Config: no ip route-cache

Timelineinfo

12/10/1992 🔍
12/10/1992 +0 days 🔍
12/10/1992 +0 days 🔍
06/16/2014 +7858 days 🔍
10/26/2025 +4150 days 🔍

Sourcesinfo

Vendor: cisco.com

Advisory: CERT CA-1992-20
Status: Confirmed

CVE: CVE-1999-1306 (🔍)
GCVE (CVE): GCVE-0-1999-1306
GCVE (VulDB): GCVE-100-13652
Vulnerability Center: 2058

See also: 🔍

Entryinfo

Created: 06/16/2014 17:55
Updated: 10/26/2025 21:07
Changes: 06/16/2014 17:55 (49), 01/13/2018 12:44 (6), 06/18/2024 11:32 (17), 10/26/2025 21:07 (5)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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