CVE-2021-0249Network attack vector

Remote code execution via crafted packet overflow

Published Apr 22, 2021 · Updated Sep 16, 2024

Buffer overflow in the PFE of Juniper Networks Junos OS on affected SRX Series releases allows remote attackers to execute code. The PFE copies data from a crafted packet sent to or through the device without adequately checking the destination buffer size, enabling code or command execution. UTM services must be configured; successful exploitation can take over or otherwise disrupt the device, and Juniper identifies a corresponding UTM log indicator.

CVSS severity8.1
High
EPSS probability1.84%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in the PFE of Juniper Networks Junos OS on affected SRX Series releases allows remote attackers to execute code. The PFE copies data from a crafted packet sent to or through the device without adequately checking the destination buffer size, enabling code or command execution. UTM services must be configured; successful exploitation can take over or otherwise disrupt the device, and Juniper identifies a corresponding UTM log indicator.

The record

CVE
CVE-2021-0249
Published
Apr 22, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-120, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=15.1X49 <15.1X49-D190
  2. Affected versionversion=17.4 <17.4R2-S9 changes=[{"at":"17.4R3","status":"affected"}]
  3. Affected versionversion=18.1 <18.1R3-S9
  4. Affected versionversion=18.2 <18.2R3-S1
  5. Affected versionversion=18.3 <18.3R2-S3, 18.3R3
  6. Affected versionversion=18.4 <18.4R2-S3, 18.4R3
  7. Affected versionversion=19.1 <19.1R1-S4, 19.1R2
  8. Affected versionversion=19.2 <19.2R1-S1, 19.2R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=15.1X49 <15.1X49-D190; version=17.4 <17.4R2-S9 changes=[{"at":"17.4R3","status":"affected"}]; version=18.1 <18.1R3-S9; version=18.2 <18.2R3-S1; version=18.3 <18.3R2-S3, 18.3R3; version=18.4 <18.4R2-S3, 18.4R3; version=19.1 <19.1R1-S4, 19.1R2; version=19.2 <19.2R1-S1, 19.2R2

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C
8.1Juniper Networks, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1190Exploit Public-Facing Application

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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