CVE-2025-21596

Packet-processing interruption via repeated chassis environment query

Published Jan 9, 2025 · Updated Jan 9, 2025

Improper exception handling in Junos OS on SRX1500, SRX4100, and SRX4200 devices allows local users to interrupt packet processing. The command-line handler for show chassis environment pem fails to handle an exceptional condition and crashes chassisd; repeated invocations prevent the daemon from restarting. Low-privileged authenticated CLI access is required, and a single invocation causes a temporary restart while repetition sustains the outage.

CVSS severity6.8
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in Junos OS on SRX1500, SRX4100, and SRX4200 devices allows local users to interrupt packet processing. The command-line handler for show chassis environment pem fails to handle an exceptional condition and crashes chassisd; repeated invocations prevent the daemon from restarting. Low-privileged authenticated CLI access is required, and a single invocation causes a temporary restart while repetition sustains the outage.

The record

CVE
CVE-2025-21596
Published
Jan 9, 2025
Updated
Jan 9, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-755, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Jan 9, 2025Record 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=0 <21.4R3-S9
  2. Affected versionversion=22.2 <22.2R3-S5
  3. Affected versionversion=22.3 <22.3R3-S4
  4. Affected versionversion=22.4 <22.4R3-S4
  5. Affected versionversion=23.2 <23.2R2-S3
  6. Affected versionversion=23.4 <23.4R2-S1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <21.4R3-S9; version=22.2 <22.2R3-S5; version=22.3 <22.3R3-S4; version=22.4 <22.4R3-S4; version=23.2 <23.2R2-S3; version=23.4 <23.4R2-S1

Published CVSS scores

5.5Juniper NetworksCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.8Juniper NetworksCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/AU:N/R:U/RE:M

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499Endpoint Denial of Service

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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