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JunosOperating system · Juniper

CVE-2025-30656

HIGH · 7.5 CVSS v3.1 Published 2025-04-09
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An Improper Handling of Additional Special Element vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series with MS-MPC, MS-MIC and SPC3, and SRX Series, allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If the SIP ALG processes specifically formatted SIP invites, a memory corruption will occur which will lead to a crash of the FPC processing these packets. Although the system will automatically recover with the restart of the FPC, subsequent SIP invites will cause the crash again and lead to a sustained DoS. This issue affects Junos OS on MX Series and SRX Series:  * all versions before 21.2R3-S9, * 21.4 versions before 21.4R3-S10, * 22.2 versions before 22.2R3-S6, * 22.4 versions before 22.4R3-S5, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2-S3, * 24.2 versions before 24.2R1-S2, 24.2R2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A memory corruption vulnerability exists in the SIP Application Layer Gateway (ALG) on Juniper MX and SRX Series devices. When the SIP ALG processes specially formatted SIP INVITE packets, improper handling of special elements in the SIP message triggers memory corruption, causing the FPC to crash. While the system auto-recovers, subsequent SIP INVITEs will cause repeated crashes, creating a sustained DoS condition.

MitigationUpgrade Junos OS to a fixed version (21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, 24.2R1-S2, or 24.2R2) per the Juniper advisory. Alternatively, disable the SIP ALG if not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:< 21.2= 21.2= 21.4= 22.2= 22.4= 23.2= 23.4= 24.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify the Junos OS version installed
    Run 'show version' on the device CLI and note the version number (for example: 21.2R3, 22.4R1, etc.)
    Affected if The installed version matches any of the following: < 21.2, 21.2, 21.4, 22.2, 22.4, 23.2, 23.4, or 24.2 (or the R1/R2/R3 sub-versions within these releases that are not in the fixed releases)
  2. Confirm SIP ALG is enabled
    Run 'show system services alg' or inspect the configuration under 'set system services alg' to see if the SIP ALG module is active
    Affected if SIP ALG is enabled and running on the device (the vulnerability only affects systems where the SIP ALG is turned on)
  3. Check for recent FPC crashes
    Run 'show chassis fpc' and 'show log messages' (or 'show system crash') to look for recent FPC restart events or SIP-related error messages
    Affected if Recent FPC crashes have occurred and are correlated with SIP INVITE traffic processing

A device is affected if it runs a vulnerable Junos version listed above AND has the SIP ALG feature enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 21.2 or later
Fixed in 21.2
Interim mitigation

Upgrade Junos OS to a fixed version (21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, 24.2R1-S2, or 24.2R2) per the Juniper advisory. Alternatively, disable the SIP ALG if not required.

Recommended fix High confidence

Upgrade to the minimum fixed version for your branch: 21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, or 24.2R2 (or later)

  1. 1. Identify the current Junos OS version on the affected MX Series (with MS-MPC, MS-MIC, SPC3) or SRX Series devices using 'show version'
  2. 2. Determine which branch (21.2, 21.4, 22.2, 22.4, 23.2, 23.4, or 24.2) the current version belongs to
  3. 3. For each branch, upgrade to the minimum fixed version: 21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, or 24.2R2 (or 24.2R1-S2) respectively
  4. 4. Alternatively, upgrade to the most recent available release for your hardware platform from https://supportportal.juniper.net
  5. 5. After upgrade, verify the SIP ALG is functioning properly with 'show security alg sip'
  6. 6. Test with legitimate SIP traffic to confirm no crashes occur
  7. 7. Monitor FPC stability with 'show chassis fpc' after processing SIP invites
Caveat Review Juniper release notes for your target version for any known incompatibilities or configuration changes required; some older hardware platforms may have limited upgrade paths

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-30656 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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