CVE-2024-21620Network attack vector

Command execution via reflected J-Web debug output

Published Jan 25, 2024 · Updated May 29, 2025

Cross-site scripting in J-Web on affected Junos OS releases allows attackers to execute commands with a visiting user's permissions. In webauth_operation.php, a specific emit_debug_note invocation echoes attacker-controlled data into the generated page without neutralizing it. Exploitation requires a target to visit the crafted URL; script execution then inherits that user's J-Web permissions and can issue administrative commands when the target is an administrator.

CVSS severity8.8
High
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in J-Web on affected Junos OS releases allows attackers to execute commands with a visiting user's permissions. In webauth_operation.php, a specific emit_debug_note invocation echoes attacker-controlled data into the generated page without neutralizing it. Exploitation requires a target to visit the crafted URL; script execution then inherits that user's J-Web permissions and can issue administrative commands when the target is an administrator.

The record

CVE
CVE-2024-21620
Published
Jan 25, 2024
Updated
May 29, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 25, 2024CVE publishedPublication date reported by the CVE source.
  2. May 29, 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 <20.4R3-S10
  2. Affected versionversion=21.2 <21.2R3-S8
  3. Affected versionversion=21.4 <21.4R3-S6
  4. Affected versionversion=22.1 <22.1R3-S5
  5. Affected versionversion=22.2 <22.2R3-S3
  6. Affected versionversion=22.3 <22.3R3-S2
  7. Affected versionversion=22.4 <22.4R3-S1
  8. Affected versionversion=23.2 <23.2R2
  9. Affected versionversion=23.4 <23.4R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <20.4R3-S10; version=21.2 <21.2R3-S8; version=21.4 <21.4R3-S6; version=22.1 <22.1R3-S5; version=22.2 <22.2R3-S3; version=22.3 <22.3R3-S2; version=22.4 <22.4R3-S1; version=23.2 <23.2R2; version=23.4 <23.4R2

Published CVSS scores

8.8Juniper NetworksCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001Malicious Link

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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