CVE-2021-27853
MEDIUM
Published Sep 27, 20223y ago · Modified Jun 17, 20261w ago
4.7 CVSS 3.1
Published Sep 27, 2022 3y ago
Last Modified Jun 17, 2026 1w ago
Description
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.
CVSS Details
Base Score
Exploitability
Impact
Vector string
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N Attack Vector Adjacent
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Changed
Confidentiality None
Integrity Low
Availability None
Threat Intelligence
No active exploitation signals — not in CISA KEV and no EPSS score yet.
Exploit & Patch Status
Public Exploit Known
No Patch Available
Weaknesses 1
CWE-290
Affected Products 312
| Vendor | Product | Version | Range |
|---|---|---|---|
| ieee | ieee_802.2 | * | ≤802.2h-1997 |
| ietf | p802.1q | * | ≤d1.0 |
| cisco | catalyst_6503-e_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6503-e | * | any |
| cisco | catalyst_6504-e_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6504-e | * | any |
| cisco | catalyst_6506-e_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6506-e | * | any |
| cisco | catalyst_6509-e_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6509-e | * | any |
| cisco | catalyst_6509-neb-a_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6509-neb-a | * | any |
| cisco | catalyst_6509-v-e_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6509-v-e | * | any |
| cisco | catalyst_6513-e_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6513-e | * | any |
| cisco | catalyst_6807-xl_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6807-xl | * | any |
| cisco | catalyst_6840-x_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6840-x | * | any |
| cisco | catalyst_6880-x_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6880-x | * | any |
| cisco | catalyst_c6816-x-le_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_c6816-x-le | * | any |
| cisco | catalyst_c6824-x-le-40g_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_c6824-x-le-40g | * | any |
| cisco | catalyst_c6832-x-le_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_c6832-x-le | * | any |
| cisco | catalyst_c6840-x-le-40g_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_c6840-x-le-40g | * | any |
| cisco | catalyst_6800ia_firmware | 15.5\(01.01.85\)sy07 | any |
| cisco | catalyst_6800ia | * | any |
| cisco | ios_xe | 17.3.3 | any |
| cisco | ios_xe | 15.2\(07\)e02 | any |
| cisco | ios_xe | 15.2\(07\)e03 | any |
| cisco | ios_xe | 17.4.1 | any |
| cisco | ios_xe | 17.6.1 | any |
| cisco | catalyst_3650-12x48fd-e | * | any |
| cisco | catalyst_3650-12x48fd-l | * | any |
| cisco | catalyst_3650-12x48fd-s | * | any |
| cisco | catalyst_3650-12x48uq-e | * | any |
| cisco | catalyst_3650-12x48uq-l | * | any |
| cisco | catalyst_3650-12x48uq-s | * | any |
| cisco | catalyst_3650-12x48ur-e | * | any |
| cisco | catalyst_3650-12x48ur-l | * | any |
| cisco | catalyst_3650-12x48ur-s | * | any |
| cisco | catalyst_3650-12x48uz-e | * | any |
| cisco | catalyst_3650-12x48uz-l | * | any |
| cisco | catalyst_3650-12x48uz-s | * | any |
| cisco | catalyst_3650-24pd-e | * | any |
| cisco | catalyst_3650-24pd-l | * | any |
| cisco | catalyst_3650-24pd-s | * | any |
| cisco | catalyst_3650-24pdm-e | * | any |
| cisco | catalyst_3650-24pdm-l | * | any |
| cisco | catalyst_3650-24pdm-s | * | any |
| cisco | catalyst_3650-24ps-e | * | any |
| cisco | catalyst_3650-24ps-l | * | any |
| cisco | catalyst_3650-24ps-s | * | any |
| cisco | catalyst_3650-24td-e | * | any |
| cisco | catalyst_3650-24td-l | * | any |
| cisco | catalyst_3650-24td-s | * | any |
| cisco | catalyst_3650-24ts-e | * | any |
| cisco | catalyst_3650-24ts-l | * | any |
| cisco | catalyst_3650-24ts-s | * | any |
| cisco | catalyst_3650-48fd-e | * | any |
| cisco | catalyst_3650-48fd-l | * | any |
| cisco | catalyst_3650-48fd-s | * | any |
| cisco | catalyst_3650-48fq-e | * | any |
| cisco | catalyst_3650-48fq-l | * | any |
| cisco | catalyst_3650-48fq-s | * | any |
| cisco | catalyst_3650-48fqm-e | * | any |
| cisco | catalyst_3650-48fqm-l | * | any |
| cisco | catalyst_3650-48fqm-s | * | any |
| cisco | catalyst_3650-48fs-e | * | any |
| cisco | catalyst_3650-48fs-l | * | any |
| cisco | catalyst_3650-48fs-s | * | any |
| cisco | catalyst_3650-48pd-e | * | any |
| cisco | catalyst_3650-48pd-l | * | any |
| cisco | catalyst_3650-48pd-s | * | any |
| cisco | catalyst_3650-48pq-e | * | any |
| cisco | catalyst_3650-48pq-l | * | any |
| cisco | catalyst_3650-48pq-s | * | any |
| cisco | catalyst_3650-48ps-e | * | any |
| cisco | catalyst_3650-48ps-l | * | any |
| cisco | catalyst_3650-48ps-s | * | any |
| cisco | catalyst_3650-48td-e | * | any |
| cisco | catalyst_3650-48td-l | * | any |
| cisco | catalyst_3650-48td-s | * | any |
| cisco | catalyst_3650-48tq-e | * | any |
| cisco | catalyst_3650-48tq-l | * | any |
| cisco | catalyst_3650-48tq-s | * | any |
| cisco | catalyst_3650-48ts-e | * | any |
| cisco | catalyst_3650-48ts-l | * | any |
| cisco | catalyst_3650-48ts-s | * | any |
| cisco | catalyst_3650-8x24pd-e | * | any |
| cisco | catalyst_3650-8x24pd-l | * | any |
| cisco | catalyst_3650-8x24pd-s | * | any |
| cisco | catalyst_3650-8x24uq-e | * | any |
| cisco | catalyst_3650-8x24uq-l | * | any |
| cisco | catalyst_3650-8x24uq-s | * | any |
| cisco | catalyst_3850-12s-e | * | any |
| cisco | catalyst_3850-12s-s | * | any |
| cisco | catalyst_3850-12xs-e | * | any |
| cisco | catalyst_3850-12xs-s | * | any |
| cisco | catalyst_3850-16xs-e | * | any |
| cisco | catalyst_3850-16xs-s | * | any |
| cisco | catalyst_3850-24p-e | * | any |
| cisco | catalyst_3850-24p-l | * | any |
| cisco | catalyst_3850-24pw-s | * | any |
| cisco | catalyst_3850-24s-e | * | any |
| cisco | catalyst_3850-24s-s | * | any |
| cisco | catalyst_3850-24t-e | * | any |
| cisco | catalyst_3850-24t-l | * | any |
| cisco | catalyst_3850-24t-s | * | any |
| cisco | catalyst_3850-24u-e | * | any |
| cisco | catalyst_3850-24u-l | * | any |
| cisco | catalyst_3850-24u-s | * | any |
| cisco | catalyst_3850-24xs-e | * | any |
| cisco | catalyst_3850-24xs-s | * | any |
| cisco | catalyst_3850-24xu-e | * | any |
| cisco | catalyst_3850-24xu-l | * | any |
| cisco | catalyst_3850-24xu-s | * | any |
| cisco | catalyst_3850-32xs-e | * | any |
| cisco | catalyst_3850-32xs-s | * | any |
| cisco | catalyst_3850-48f-e | * | any |
| cisco | catalyst_3850-48f-l | * | any |
| cisco | catalyst_3850-48f-s | * | any |
| cisco | catalyst_3850-48p-e | * | any |
| cisco | catalyst_3850-48p-l | * | any |
| cisco | catalyst_3850-48p-s | * | any |
| cisco | catalyst_3850-48pw-s | * | any |
| cisco | catalyst_3850-48t-e | * | any |
| cisco | catalyst_3850-48t-l | * | any |
| cisco | catalyst_3850-48t-s | * | any |
| cisco | catalyst_3850-48u-e | * | any |
| cisco | catalyst_3850-48u-l | * | any |
| cisco | catalyst_3850-48u-s | * | any |
| cisco | catalyst_3850-48xs-e | * | any |
| cisco | catalyst_3850-48xs-f-e | * | any |
| cisco | catalyst_3850-48xs-f-s | * | any |
| cisco | catalyst_3850-48xs-s | * | any |
| cisco | catalyst_9200 | * | any |
| cisco | catalyst_9200cx | * | any |
| cisco | catalyst_9200l | * | any |
| cisco | catalyst_9300 | * | any |
| cisco | catalyst_9300l | * | any |
| cisco | catalyst_9300lm | * | any |
| cisco | catalyst_9300x | * | any |
| cisco | catalyst_9400 | * | any |
| cisco | catalyst_9500 | * | any |
| cisco | catalyst_9500h | * | any |
| cisco | catalyst_9600 | * | any |
| cisco | catalyst_9600x | * | any |
| cisco | catalyst_c3850-12x48u-e | * | any |
| cisco | catalyst_c3850-12x48u-l | * | any |
| cisco | catalyst_c3850-12x48u-s | * | any |
| cisco | meraki_ms390_firmware | * | any |
| cisco | meraki_ms390 | * | any |
| cisco | meraki_ms210_firmware | * | any |
| cisco | meraki_ms210 | * | any |
| cisco | meraki_ms225_firmware | * | any |
| cisco | meraki_ms225 | * | any |
| cisco | meraki_ms250_firmware | * | any |
| cisco | meraki_ms250 | * | any |
| cisco | meraki_ms350_firmware | * | any |
| cisco | meraki_ms350 | * | any |
| cisco | meraki_ms355_firmware | * | any |
| cisco | meraki_ms355 | * | any |
| cisco | meraki_ms410_firmware | * | any |
| cisco | meraki_ms410 | * | any |
| cisco | meraki_ms420_firmware | * | any |
| cisco | meraki_ms420 | * | any |
| cisco | meraki_ms425_firmware | * | any |
| cisco | meraki_ms425 | * | any |
| cisco | meraki_ms450_firmware | * | any |
| cisco | meraki_ms450 | * | any |
| cisco | nexus_93180yc-ex_firmware | 9.3\(5\) | any |
| cisco | nexus_93180yc-ex | * | any |
| cisco | nexus_93180yc-fx_firmware | 9.3\(5\) | any |
| cisco | nexus_93180yc-fx | * | any |
| cisco | nexus_93180yc-fx3_firmware | 9.3\(5\) | any |
| cisco | nexus_93180yc-fx3 | * | any |
| cisco | nexus_93240yc-fx2_firmware | 9.3\(5\) | any |
| cisco | nexus_93240yc-fx2 | * | any |
| cisco | nexus_93360yc-fx2_firmware | 9.3\(5\) | any |
| cisco | nexus_93360yc-fx2 | * | any |
| cisco | nexus_93120tx_firmware | 9.3\(5\) | any |
| cisco | nexus_93120tx | * | any |
| cisco | nexus_93108tc-ex_firmware | 9.3\(5\) | any |
| cisco | nexus_93108tc-ex | * | any |
| cisco | nexus_9348gc-fxp_firmware | 9.3\(5\) | any |
| cisco | nexus_9348gc-fxp | * | any |
| cisco | nexus_93108tc-fx_firmware | 9.3\(5\) | any |
| cisco | nexus_93108tc-fx | * | any |
| cisco | nexus_93108tc-fx3p_firmware | 9.3\(5\) | any |
| cisco | nexus_93108tc-fx3p | * | any |
| cisco | nexus_93216tc-fx2_firmware | 9.3\(5\) | any |
| cisco | nexus_93216tc-fx2 | * | any |
| cisco | n9k-c9316d-gx_firmware | 9.3\(5\) | any |
| cisco | n9k-c9316d-gx | * | any |
| cisco | n9k-c93600cd-gx_firmware | 9.3\(5\) | any |
| cisco | n9k-c93600cd-gx | * | any |
| cisco | n9k-c9332d-gx2b_firmware | 9.3\(5\) | any |
| cisco | n9k-c9332d-gx2b | * | any |
| cisco | n9k-c9348d-gx2a_firmware | 9.3\(5\) | any |
| cisco | n9k-c9348d-gx2a | * | any |
| cisco | n9k-c9364d-gx2a_firmware | 9.3\(5\) | any |
| cisco | n9k-c9364d-gx2a | * | any |
| cisco | n9k-x97160yc-ex_firmware | 9.3\(5\) | any |
| cisco | n9k-x97160yc-ex | * | any |
| cisco | n9k-x9788tc-fx_firmware | 9.3\(5\) | any |
| cisco | n9k-x9788tc-fx | * | any |
| cisco | n9k-x9564px_firmware | 9.3\(5\) | any |
| cisco | n9k-x9564px | * | any |
| cisco | n9k-x9464px_firmware | 9.3\(5\) | any |
| cisco | n9k-x9464px | * | any |
| cisco | n9k-x9564tx_firmware | 9.3\(5\) | any |
| cisco | n9k-x9564tx | * | any |
| cisco | n9k-x9464tx2_firmware | 9.3\(5\) | any |
| cisco | n9k-x9464tx2 | * | any |
| cisco | nexus_9636pq_firmware | 9.3\(5\) | any |
| cisco | nexus_9636pq | * | any |
| cisco | nexus_x9636q-r_firmware | 9.3\(5\) | any |
| cisco | nexus_x9636q-r | * | any |
| cisco | nexus_9536pq_firmware | 9.3\(5\) | any |
| cisco | nexus_9536pq | * | any |
| cisco | nexus_9432pq_firmware | 9.3\(5\) | any |
| cisco | nexus_9432pq | * | any |
| cisco | nexus_9736pq_firmware | 9.3\(5\) | any |
| cisco | nexus_9736pq | * | any |
| cisco | n9k-x9736c-fx_firmware | 9.3\(5\) | any |
| cisco | n9k-x9736c-fx | * | any |
| cisco | n9k-x9732c-ex_firmware | 9.3\(5\) | any |
| cisco | n9k-x9732c-ex | * | any |
| cisco | n9k-x9732c-fx_firmware | 9.3\(5\) | any |
| cisco | n9k-x9732c-fx | * | any |
| cisco | n9k-x9736c-ex_firmware | 9.3\(5\) | any |
| cisco | n9k-x9736c-ex | * | any |
| cisco | n9k-x9636c-rx_firmware | 9.3\(5\) | any |
| cisco | n9k-x9636c-rx | * | any |
| cisco | n9k-x9636c-r_firmware | 9.3\(5\) | any |
| cisco | n9k-x9636c-r | * | any |
| cisco | n9k-x9432c-s_firmware | 9.3\(5\) | any |
| cisco | n9k-x9432c-s | * | any |
| cisco | nexus_9716d-gx_firmware | 9.3\(5\) | any |
| cisco | nexus_9716d-gx | * | any |
| cisco | nexus_9504_firmware | 9.3\(5\) | any |
| cisco | nexus_9504 | * | any |
| cisco | nexus_9508_firmware | 9.3\(5\) | any |
| cisco | nexus_9508 | * | any |
| cisco | nexus_9516_firmware | 9.3\(5\) | any |
| cisco | nexus_9516 | * | any |
| cisco | nexus_92160yc-x_firmware | 9.3\(5\) | any |
| cisco | nexus_92160yc-x | * | any |
| cisco | nexus_9272q_firmware | 9.3\(5\) | any |
| cisco | nexus_9272q | * | any |
| cisco | nexus_92304qc_firmware | 9.3\(5\) | any |
| cisco | nexus_92304qc | * | any |
| cisco | nexus_9236c_firmware | 9.3\(5\) | any |
| cisco | nexus_9236c | * | any |
| cisco | nexus_92300yc_firmware | 9.3\(5\) | any |
| cisco | nexus_92300yc | * | any |
| cisco | nexus_92348gc-x_firmware | 9.3\(5\) | any |
| cisco | nexus_92348gc-x | * | any |
| cisco | nexus_9364c_firmware | 9.3\(5\) | any |
| cisco | nexus_9364c | * | any |
| cisco | nexus_9336c-fx2_firmware | 9.3\(5\) | any |
| cisco | nexus_9336c-fx2 | * | any |
| cisco | nexus_9336c-fx2-e_firmware | 9.3\(5\) | any |
| cisco | nexus_9336c-fx2-e | * | any |
| cisco | nexus_9332c_firmware | 9.3\(5\) | any |
| cisco | nexus_9332c | * | any |
| cisco | nexus_9364c-gx_firmware | 9.3\(5\) | any |
| cisco | nexus_9364c-gx | * | any |
| cisco | nexus_9800_firmware | 9.3\(5\) | any |
| cisco | nexus_9800 | * | any |
| cisco | sf500-24_firmware | 3.0.0.61 | any |
| cisco | sf500-24 | * | any |
| cisco | sf-500-24mp_firmware | 3.0.0.61 | any |
| cisco | sf-500-24mp | * | any |
| cisco | sf500-24p_firmware | 3.0.0.61 | any |
| cisco | sf500-24p | * | any |
| cisco | sf500-48_firmware | 3.0.0.61 | any |
| cisco | sf500-48 | * | any |
| cisco | sf500-48mp_firmware | 3.0.0.61 | any |
| cisco | sf500-48mp | * | any |
| cisco | sf500-18p_firmware | 3.0.0.61 | any |
| cisco | sf500-18p | * | any |
| cisco | sg500-28_firmware | 3.0.0.61 | any |
| cisco | sg500-28 | * | any |
| cisco | sg500-28mpp_firmware | 3.0.0.61 | any |
| cisco | sg500-28mpp | * | any |
| cisco | sg500-28p_firmware | 3.0.0.61 | any |
| cisco | sg500-28p | * | any |
| cisco | sg500-52_firmware | 3.0.0.61 | any |
| cisco | sg500-52 | * | any |
| cisco | sg500-52mp_firmware | 3.0.0.61 | any |
| cisco | sg500-52mp | * | any |
| cisco | sg500-52p_firmware | 3.0.0.61 | any |
| cisco | sg500-52p | * | any |
| cisco | sg500x-24_firmware | 3.0.0.61 | any |
| cisco | sg500x-24 | * | any |
| cisco | sg500x-24mpp_firmware | 3.0.0.61 | any |
| cisco | sg500x-24mpp | * | any |
| cisco | sg500x-24p_firmware | 3.0.0.61 | any |
| cisco | sg500x-24p | * | any |
| cisco | sg500x-48_firmware | 3.0.0.61 | any |
| cisco | sg500x-48 | * | any |
| cisco | sg500x-48mpp_firmware | 3.0.0.61 | any |
| cisco | sg500x-48mpp | * | any |
| cisco | sg500x-48p_firmware | 3.0.0.61 | any |
| cisco | sg500x-48p | * | any |
References 7
- blog.champtar.fr https://blog.champtar.fr/VLAN0_LLC_SNAP/
- datatracker.ietf.org https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/
- kb.cert.org https://kb.cert.org/vuls/id/855201
- standards.ieee.org https://standards.ieee.org/ieee/802.1Q/10323/
- standards.ieee.org https://standards.ieee.org/ieee/802.2/1048/
- tools.cisco.com https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-VU855201-J3z8CKTX
- kb.cert.org https://www.kb.cert.org/vuls/id/855201
Remediation
No remediation data recorded yet
Check vendor advisories and the NVD entry for patch availability.