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JunosOperating system · Juniper

CVE-2026-21914

HIGH · 7.5 CVSS v3.1 Published 2026-01-15
Fix available
A fix is available. Upgrade to 22.4 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 Locking vulnerability in the GTP plugin of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos). If an SRX Series device receives a specifically malformed GPRS Tunnelling Protocol (GTP) Modify Bearer Request message, a lock is acquired and never released. This results in other threads not being able to acquire a lock themselves, causing a watchdog timeout leading to FPC crash and restart. This issue leads to a complete traffic outage until the device has automatically recovered. This issue affects Junos OS on SRX Series: * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2-S6, * 24.2 versions before 24.2R2-S3, * 24.4 versions before 24.4R2-S2, * 25.2 versions before 25.2R1-S1, 25.2R2.

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 race condition or improper lock handling in the GTP plugin causes a deadlock when a malformed GTP Modify Bearer Request is received. The lock is acquired but never released, blocking other threads from acquiring the same lock, triggering a watchdog timeout that crashes and restarts the FPC (Flow Processing Card), causing complete traffic outage until auto-recovery.

MitigationUpgrade Junos OS on SRX Series to the fixed versions (22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S2, 25.2R1-S1, or 25.2R2 or later) to patch the improper locking vulnerability in the GTP plugin.

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:< 22.4= 22.4= 23.2= 23.4= 24.2= 24.4= 25.2

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. Check Junos OS version
    Run 'show version' on the device CLI and locate the Junos OS version number (e.g., 22.4, 23.2, 23.4, 24.2, 24.4, 25.2)
    Affected if The installed version is any of: < 22.4, 22.4, 23.2, 23.4, 24.2, 24.4, or 25.2 (versions not equal to the fixed releases: 22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S2, 25.2R1-S1, or 25.2R2)
  2. Verify GTP service is enabled
    Run 'show services gtps statistics' or check configuration with 'show configuration | match gtp' to see if GTP service is configured and active
    Affected if GTP service is enabled and the device is processing GTP traffic (the flaw requires GTP to be running)
  3. Check for FPC crash or restart logs
    Run 'show log messages' and search for patterns like 'FPC.*crash', 'watchdog timeout', 'FPC.*restart', or 'GTP' related errors using '| match' filters
    Affected if Recent FPC crashes, watchdog timeouts, or GTP plugin errors appear in the system logs (indicating the deadlock may have already been triggered)
  4. Check FPC status and health
    Run 'show chassis fpc' to view the status of Flow Processing Cards and look for any FPCs in 'Online' but unstable state, or check 'show system core-dumps' for recent core files
    Affected if FPC shows unexpected restarts, offline status, or core dump files exist from recent crashes

You are affected if GTP service is enabled AND your Junos version falls within the affected list (< 22.4, 22.4, 23.2, 23.4, 24.2, 24.4, or 25.2) and you have not applied one of the fixed subversions or later releases.

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 22.4 or later
Fixed in 22.4
Interim mitigation

Upgrade Junos OS on SRX Series to the fixed versions (22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S2, 25.2R1-S1, or 25.2R2 or later) to patch the improper locking vulnerability in the GTP plugin.

Recommended fix High confidence

22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S2, or 25.2R2 (depending on current branch)

  1. 1. Identify the current Junos OS version on the SRX Series device using 'show version'
  2. 2. Determine which version branch your device is running (22.4, 23.2, 23.4, 24.2, 24.4, or 25.2)
  3. 3. For 22.4 branch: upgrade to 22.4R3-S8 or later
  4. 4. For 23.2 branch: upgrade to 23.2R2-S5 or later
  5. 5. For 23.4 branch: upgrade to 23.4R2-S6 or later
  6. 6. For 24.2 branch: upgrade to 24.2R2-S3 or later
  7. 7. For 24.4 branch: upgrade to 24.4R2-S2 or later
  8. 8. For 25.2 branch: upgrade to 25.2R1-S1 or 25.2R2 or later
Caveat Standard Junos upgrade precautions apply - verify hardware compatibility and test in lab environment before production deployment

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,300
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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-2026-21914 in production — separate from our analysis above.

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What this is

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