CVE-2021-26111

Memory exhaustion via crafted discovery packets

Published Jun 1, 2021 · Updated Oct 25, 2024

Memory leak in affected Fortinet FortiSwitch releases allows attackers on adjacent networks to exhaust memory with crafted discovery packets. The LLDP, CDP, and EDP packet-processing path retains allocated memory after packet lifetime rather than releasing it. The affected releases are 3.6.11 and earlier, 6.0.0 through 6.0.6, 6.2.0 through 6.2.6, and 6.4.0 through 6.4.6; no authentication or user interaction is required, but the attacker must share an adjacent network segment, and sustained traffic interrupts switching service.

CVSS severity6.5
Medium
EPSS probability0.38%
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

Memory leak in affected Fortinet FortiSwitch releases allows attackers on adjacent networks to exhaust memory with crafted discovery packets. The LLDP, CDP, and EDP packet-processing path retains allocated memory after packet lifetime rather than releasing it. The affected releases are 3.6.11 and earlier, 6.0.0 through 6.0.6, 6.2.0 through 6.2.6, and 6.4.0 through 6.4.6; no authentication or user interaction is required, but the attacker must share an adjacent network segment, and sustained traffic interrupts switching service.

The record

CVE
CVE-2021-26111
Published
Jun 1, 2021
Updated
Oct 25, 2024
Vendor
Fortinet
Product
FortiSwitch
Classifications
CWE-401, T1499.003
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 25, 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=FortiSwitch 6.4.0 to 6.4.6, 6.2.0 to 6.2.6, 6.0.0 to 6.0.6, 3.6.11 and below

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Fortinet · FortiSwitchversion=FortiSwitch 6.4.0 to 6.4.6, 6.2.0 to 6.2.6, 6.0.0 to 6.0.6, 3.6.11 and below

Published CVSS scores

3.3NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:P
6.5Fortinet, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/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-401Missing Release of Memory after Effective Lifetime
T1499.003Application Exhaustion Flood

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