CVE-2021-27853
Layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection can be bypassed using combinations of VLAN 0 headers and LLC/SNAP headers.
- Score
- CVSS 3.1 4.7 Medium
- Status
- Modified - cret@cert.org
- Published
- 2022-09-27
- Last modified
- 2025-11-04
- Weaknesses
- CWE-290
Affected products
- Catalyst 6503-e Firmware (Cisco)
- Catalyst 6504-e Firmware (Cisco)
- Catalyst 6506-e Firmware (Cisco)
- Catalyst 6509-e Firmware (Cisco)
- Catalyst 6509-neb-a Firmware (Cisco)
- Catalyst 6509-v-e Firmware (Cisco)
- Catalyst 6513-e Firmware (Cisco)
- Catalyst 6800ia Firmware (Cisco)
- Catalyst 6807-xl Firmware (Cisco)
- Catalyst 6840-x Firmware (Cisco)
- Catalyst 6880-x Firmware (Cisco)
- Catalyst C6816-x-le Firmware (Cisco)
- Catalyst C6824-x-le-40g Firmware (Cisco)
- Catalyst C6832-x-le Firmware (Cisco)
- Catalyst C6840-x-le-40g Firmware (Cisco)
- Ios Xe (Cisco)
- Meraki Ms210 Firmware (Cisco)
- Meraki Ms225 Firmware (Cisco)
- Meraki Ms250 Firmware (Cisco)
- Meraki Ms350 Firmware (Cisco)
- Meraki Ms355 Firmware (Cisco)
- Meraki Ms390 Firmware (Cisco)
- Meraki Ms410 Firmware (Cisco)
- Meraki Ms420 Firmware (Cisco)
- Meraki Ms425 Firmware (Cisco)
- Meraki Ms450 Firmware (Cisco)
- N9k-c9316d-gx Firmware (Cisco)
- N9k-c9332d-gx2b Firmware (Cisco)
- N9k-c9348d-gx2a Firmware (Cisco)
- N9k-c93600cd-gx Firmware (Cisco)
- N9k-c9364d-gx2a Firmware (Cisco)
- N9k-x9432c-s Firmware (Cisco)
- N9k-x9464px Firmware (Cisco)
- N9k-x9464tx2 Firmware (Cisco)
- N9k-x9564px Firmware (Cisco)
- N9k-x9564tx Firmware (Cisco)
- N9k-x9636c-r Firmware (Cisco)
- N9k-x9636c-rx Firmware (Cisco)
- N9k-x97160yc-ex Firmware (Cisco)
- N9k-x9732c-ex Firmware (Cisco)
- N9k-x9732c-fx Firmware (Cisco)
- N9k-x9736c-ex Firmware (Cisco)
- N9k-x9736c-fx Firmware (Cisco)
- N9k-x9788tc-fx Firmware (Cisco)
- Nexus 92160yc-x Firmware (Cisco)
- Nexus 92300yc Firmware (Cisco)
- Nexus 92304qc Firmware (Cisco)
- Nexus 92348gc-x Firmware (Cisco)
- Nexus 9236c Firmware (Cisco)
- Nexus 9272q Firmware (Cisco)
- Nexus 93108tc-ex Firmware (Cisco)
- Nexus 93108tc-fx3p Firmware (Cisco)
- Nexus 93108tc-fx Firmware (Cisco)
- Nexus 93120tx Firmware (Cisco)
- Nexus 93180yc-ex Firmware (Cisco)
- Nexus 93180yc-fx3 Firmware (Cisco)
- Nexus 93180yc-fx Firmware (Cisco)
- Nexus 93216tc-fx2 Firmware (Cisco)
- Nexus 93240yc-fx2 Firmware (Cisco)
- Nexus 9332c Firmware (Cisco)
- Nexus 93360yc-fx2 Firmware (Cisco)
- Nexus 9336c-fx2-e Firmware (Cisco)
- Nexus 9336c-fx2 Firmware (Cisco)
- Nexus 9348gc-fxp Firmware (Cisco)
- Nexus 9364c-gx Firmware (Cisco)
- Nexus 9364c Firmware (Cisco)
- Nexus 9432pq Firmware (Cisco)
- Nexus 9504 Firmware (Cisco)
- Nexus 9508 Firmware (Cisco)
- Nexus 9516 Firmware (Cisco)
- Nexus 9536pq Firmware (Cisco)
- Nexus 9636pq Firmware (Cisco)
- Nexus 9716d-gx Firmware (Cisco)
- Nexus 9736pq Firmware (Cisco)
- Nexus 9800 Firmware (Cisco)
- Nexus X9636q-r Firmware (Cisco)
- Sf-500-24mp Firmware (Cisco)
- Sf500-18p Firmware (Cisco)
- Sf500-24 Firmware (Cisco)
- Sf500-24p Firmware (Cisco)
- Sf500-48 Firmware (Cisco)
- Sf500-48mp Firmware (Cisco)
- Sg500-28 Firmware (Cisco)
- Sg500-28mpp Firmware (Cisco)
- Sg500-28p Firmware (Cisco)
- Sg500-52 Firmware (Cisco)
- Sg500-52mp Firmware (Cisco)
- Sg500-52p Firmware (Cisco)
- Sg500x-24 Firmware (Cisco)
- Sg500x-24mpp Firmware (Cisco)
- Sg500x-24p Firmware (Cisco)
- Sg500x-48 Firmware (Cisco)
- Sg500x-48mpp Firmware (Cisco)
- Sg500x-48p Firmware (Cisco)
- 802.2 (Ieee)
- Ieee 802.2 (Ieee)
- Draft-ietf-v6ops-ra-guard (Ietf)
- P802.1q (Ietf)
References
- https://blog.champtar.fr/VLAN0_LLC_SNAP/
- https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/
- https://kb.cert.org/vuls/id/855201
- https://standards.ieee.org/ieee/802.1Q/10323/
- https://standards.ieee.org/ieee/802.2/1048/
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-VU855201-J3z8CKTX
- https://www.kb.cert.org/vuls/id/855201
