CVE-2021-0262

Sustained denial of service via freed-memory access

Published Apr 22, 2021 · Updated Sep 17, 2024

Use-after-free in Junos OS PFE packet processing allows attackers to sustain a denial of service on QFX10002-60C switches. The PFE packet-processing path accesses memory after it has been freed; Juniper has not disclosed the affected routine or triggering packet sequence. Logically adjacent access is required, and repeated exploitation sustains the service interruption.

CVSS severity6.5
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Junos OS PFE packet processing allows attackers to sustain a denial of service on QFX10002-60C switches. The PFE packet-processing path accesses memory after it has been freed; Juniper has not disclosed the affected routine or triggering packet sequence. Logically adjacent access is required, and repeated exploitation sustains the service interruption.

The record

CVE
CVE-2021-0262
Published
Apr 22, 2021
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-416, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=19.1R3-S1 <19.1* changes=[{"at":"19.1R3-S3","status":"unaffected"}]
  2. Affected versionversion=19.2 <19.2R2 changes=[{"at":"19.2R2","status":"affected"},{"at":"19.2R3-S1","status":"unaffected"}]
  3. Affected versionversion=20.2 <20.2R1-S2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=19.1R3-S1 <19.1* changes=[{"at":"19.1R3-S3","status":"unaffected"}]; version=19.2 <19.2R2 changes=[{"at":"19.2R2","status":"affected"},{"at":"19.2R3-S1","status":"unaffected"}]; version=20.2 <20.2R1-S2

Published CVSS scores

6.5Juniper NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.3NVDAV:A/AC:L/Au:N/C:N/I:N/A:P

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-416Use After Free
T1499.004Endpoint Denial of Service: Application or System Exploitation

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

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Your stack

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