Security readout for executives and security teams
Plain-English summary
This CVE affects Cisco Small Business 220 Series Smart Switches through flaws in LLDP, a local network discovery protocol. A nearby attacker on the same Layer 2 network could disrupt the switch, corrupt LLDP data, or potentially execute code. This is not described as remotely exploitable from the internet.
Executive priority
Treat as a moderate infrastructure maintenance risk. It is constrained to local network adjacency, but affected switches can underpin business connectivity. Patch during the next controlled network maintenance window, sooner where untrusted devices share the same LAN.
Technical view
Cisco reports multiple LLDP implementation vulnerabilities in Small Business 220 Series Smart Switches. The CVE is CWE-120 with CVSS 3.1 score 4.3, adjacent attack vector, low complexity, no privileges, and no user interaction. Cisco says firmware updates address the vulnerabilities.
Likely exposure
Exposure is mainly internal or local-network facing: an attacker must be in the same broadcast domain as the affected switch. Risk is higher on shared, guest, unmanaged, or physically accessible LAN segments using affected Cisco small-business switches.
Exploitation context
The bundle does not cite active exploitation, and CISA KEV status is false. Exploitation requires Layer 2 adjacency, limiting reach, but unauthenticated access on the same broadcast domain is enough according to Cisco’s description.
Researcher notes
The source bundle has a naming inconsistency: the title and description cite Small Business 220 Series, while the affected field names 200 Series. Use Cisco’s advisory as the authoritative source for exact device and firmware applicability.
Mitigation direction
- Check Cisco guidance for exact affected models and fixed firmware.
- Apply Cisco firmware updates that address these LLDP vulnerabilities.
- Prioritize switches on shared, guest, or physically accessible LANs.
- Restrict untrusted devices from affected Layer 2 broadcast domains.
- Review whether LLDP exposure is necessary on untrusted edge ports.
Validation and detection
- Inventory Cisco Small Business 220 Series Smart Switches.
- Compare installed firmware against Cisco’s advisory and fixed releases.
- Map affected switches to broadcast domains with untrusted access.
- Check for unexpected reloads or LLDP database anomalies.
- Document remediation status and remaining exposed segments.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupDatabase behavior lookup
The CVE wording references database injection or access, so collection and exfiltration review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-34777 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.3MediumVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20211006 Cisco Small Business 220 Series Smart Switches Link Layer Discovery Protocol VulnerabilitiesCVE reference · vendor-advisory, x_refsource_CISCO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.