{"cve":"CVE-2021-27853","nvd":{"published":"2022-09-27T18:15:09.527","modified":"2026-06-17T03:45:31.153","status":"Modified","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","score":4.7},"cwes":["CWE-290"],"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/"],"products":["cisco: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"],"source":"nvd","synced_at":"2026-10-19T21:36:05.460296998+00:00"},"epss":{"cve":"CVE-2021-27853","score":0.00813,"percentile":0.57009,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}