CVE-2021-27854
CVE-2021-27854 is a medium-severity vulnerability in Ieee Ieee 802.2 with a CVSS 3.x base score of 4.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-290.
Key facts
- Severity: Medium (CVSS 3.x base score 4.7)
- EPSS exploit prediction: 1% (47th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-290
- Affected product: Ieee Ieee 802.2
- Published:
- Last modified:
Description
Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using combinations of VLAN 0 headers, LLC/SNAP headers, and converting frames from Ethernet to Wifi and its reverse.
Frequently asked questions
- What is CVE-2021-27854?
- Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using combinations of VLAN 0 headers, LLC/SNAP headers, and converting frames from Ethernet to Wifi and its reverse.
- How severe is CVE-2021-27854?
- CVE-2021-27854 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
- Is CVE-2021-27854 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-27854?
- CVE-2021-27854 primarily affects Ieee Ieee 802.2. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2021-27854?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2021-27854 published?
- CVE-2021-27854 was published on 2022-09-27 and last updated on 2026-06-17.
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://www.kb.cert.org/vuls/id/855201
Affected products (2)
- cpe:2.3:a:ieee:ieee_802.2:*:*:*:*:*:*:*:*
- cpe:2.3:a:ietf:p802.1q:*:*:*:*:*:*:*:*
More vulnerabilities in Ieee Ieee 802.2
- CVE-2021-27862 — Medium (CVSS 4.7): Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length…
- CVE-2021-27861 — Medium (CVSS 4.7): Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length…
- CVE-2021-27853 — Medium (CVSS 4.7): Layer 2 network filtering capabilities such as IPv6 RA guard or ARP inspection can be bypassed using combinations of…
All CVEs affecting Ieee Ieee 802.2 →
Other CWE-290 vulnerabilities
- CVE-2026-48567 — Critical (CVSS 10.0): Authentication bypass by spoofing in Azure HorizonDB allows an unauthorized attacker to elevate privileges over a…
- CVE-2026-6213 — Critical (CVSS 10.0): A vulnerability in Remote Spark SparkView before build 1122 allows an attacker to bypasses the local connection check…
- CVE-2026-39858 — Critical (CVSS 10.0): Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a high…
- CVE-2025-66570 — Critical (CVSS 10.0): cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.27.0, a vulnerability…
- CVE-2025-34063 — Critical (CVSS 10.0): A cryptographic authentication bypass vulnerability exists in OneLogin AD Connector prior to 6.1.5 due to the exposure…
- CVE-2023-22814 — Critical (CVSS 10.0): An authentication bypass issue via spoofing was discovered in the token-based authentication mechanism that could allow…