CVE-2021-1308

Router reload via unchecked LLDP header lengths

Published Apr 8, 2021 · Updated Nov 8, 2024

Denial of service in Cisco Small Business RV Series Router firmware allows attackers to reload affected routers with a malicious LLDP packet. The LLDP implementation fails to validate the lengths of certain packet header fields before processing them. Exploitation requires LLDP to be enabled and the attacker to share the router's Layer 2 broadcast domain; a successful packet forces an unexpected reload and interrupts routing service.

CVSS severity7.4
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in Cisco Small Business RV Series Router firmware allows attackers to reload affected routers with a malicious LLDP packet. The LLDP implementation fails to validate the lengths of certain packet header fields before processing them. Exploitation requires LLDP to be enabled and the attacker to share the router's Layer 2 broadcast domain; a successful packet forces an unexpected reload and interrupts routing service.

The record

CVE
CVE-2021-1308
Published
Apr 8, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco Small Business RV Series Router Firmware
Classifications
CWE-119, T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Small Business RV Series Router Firmwareversion=n/a

Published CVSS scores

7.4CiscoCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo