CVE-2023-36841Network attack vector

Remote service interruption via PFE infinite loop

Published Oct 12, 2023 · Updated Sep 18, 2024

Resource-consumption flaw in Junos OS on MX Series allows remote attackers to interrupt forwarding with malformed TCP traffic. The Packet Forwarding Engine enters an infinite loop while processing the traffic and exhausts its resources, leaving manual restart as the recovery path. Exposure requires a PPPoE interface with tcp-mss enabled; no confidentiality or integrity impact is reported.

CVSS severity7.5
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource-consumption flaw in Junos OS on MX Series allows remote attackers to interrupt forwarding with malformed TCP traffic. The Packet Forwarding Engine enters an infinite loop while processing the traffic and exhausts its resources, leaving manual restart as the recovery path. Exposure requires a PPPoE interface with tcp-mss enabled; no confidentiality or integrity impact is reported.

The record

CVE
CVE-2023-36841
Published
Oct 12, 2023
Updated
Sep 18, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 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=0 <20.4r3-s7
  2. Affected versionversion=0 <20.4R3-S7
  3. Affected versionversion=21.1r1 <21.1
  4. Affected versionversion=21.1R1 <21.1*
  5. Affected versionversion=21.2 <21.2r3-s6
  6. Affected versionversion=21.2 <21.2R3-S6
  7. Affected versionversion=21.3 <21.3r3-s5
  8. Affected versionversion=21.3 <21.3R3-S5
  9. Affected versionversion=21.4 <21.4r3-s3
  10. Affected versionversion=21.4 <21.4R3-S3
  11. Affected versionversion=22.1 <22.1r3-s4
  12. Affected versionversion=22.1 <22.1R3-S4
  13. Affected versionversion=22.2 <22.2r3
  14. Affected versionversion=22.2 <22.2R3
  15. Affected versionversion=22.3 <22.3r2-s2
  16. Affected versionversion=22.3 <22.3R2-S2, 22.3R3
  17. Affected versionversion=22.3 <22.3r3
  18. Affected versionversion=22.4 <22.4r2
  19. Affected versionversion=22.4 <22.4R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <20.4r3-s7; version=0 <20.4R3-S7; version=21.1r1 <21.1; version=21.1R1 <21.1*; version=21.2 <21.2r3-s6; version=21.2 <21.2R3-S6; version=21.3 <21.3r3-s5; version=21.3 <21.3R3-S5; version=21.4 <21.4r3-s3; version=21.4 <21.4R3-S3; version=22.1 <22.1r3-s4; version=22.1 <22.1R3-S4; version=22.2 <22.2r3; version=22.2 <22.2R3; version=22.3 <22.3r2-s2; version=22.3 <22.3R2-S2, 22.3R3; version=22.3 <22.3r3; version=22.4 <22.4r2; version=22.4 <22.4R2

Published CVSS scores

7.5Juniper NetworksCVSS:3.1/AV:N/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 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-400Uncontrolled Resource Consumption
T1499.004Application 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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