CVE-2019-1686
Cisco ASR 9000 Series Aggregation Services Routers ACL Bypass Vulnerability
- Published
- Updated
- Reserved
- Assigned by
- cisco
Description
A vulnerability in the TCP flags inspection feature for access control lists (ACLs) on Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to bypass protection offered by a configured ACL on an affected device. The vulnerability is due to incorrect processing of the ACL applied to an interface of an affected device when Cisco Express Forwarding load balancing using the 3-tuple hash algorithm is enabled. An attacker could exploit this vulnerability by sending traffic through an affected device that should otherwise be denied by the configured ACL. An exploit could allow the attacker to bypass protection offered by a configured ACL on the affected device. There are workarounds that address this vulnerability. Affected Cisco IOS XR versions are: Cisco IOS XR Software Release 5.1.1 and later till first fixed. First Fixed Releases: 6.5.2 and later, 6.6.1 and later.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ciscoCNA (assigner) | 3.0 | Medium5.8 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N |
| NVDNVD · Modified | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 1.6% · top 24% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.8.
Weakness
Affected products
- affected unspecified – < 6.5.2
- affected unspecified – < 6.6.1
What to do
Exploitation: The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
References (2)
- 20190417 Cisco ASR 9000 Series Aggregation Services Routers ACL Bypass Vulnerability (opens in a new tab)vendor-advisoryx_refsource_CISCOx_transferred
- 108026 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2019-1686)Record last updated .