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JunosOperating system · Juniper

CVE-2025-21593

MEDIUM · 6.5 CVSS v3.1 Published 2025-01-09
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
70/100
Remediation priority · Elevated
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 Control of a Resource Through its Lifetime vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker to cause a Denial-of-Service (DoS). On devices with SRv6 (Segment Routing over IPv6) enabled, an attacker can send a malformed BGP UPDATE packet which will cause the rpd to crash and restart. Continued receipt of these UPDATE packets will cause a sustained DoS condition.  This issue affects iBGP and eBGP, and both IPv4 and IPv6 are affected by this vulnerability.This issue affects Junos OS:  * All versions before 21.2R3-S9,  * from 21.4 before 21.4R3-S10,  * from 22.2 before 22.2R3-S5,  * from 22.3 before 22.3R3-S4,  * from 22.4 before 22.4R3-S3,  * from 23.2 before 23.2R2-S2,  * from 23.4 before 23.4R2; and Junos OS Evolved:  * All versions before 21.2R3-S9-EVO,  * from 21.4-EVO before 21.4R3-S10-EVO,  * from 22.2-EVO before 22.2R3-S5-EVO,  * from 22.3-EVO before 22.3R3-S4-EVO,  * from 22.4-EVO before 22.4R3-S3-EVO, * from 23.2-EVO before 23.2R2-S2-EVO,  * from 23.4-EVO before 23.4R2-EVO.

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 resource lifecycle management flaw in the Juniper rpd daemon allows an unauthenticated attacker to crash the routing process by sending malformed BGP UPDATE packets on networks with SRv6 enabled, causing repeated DoS conditions.

MitigationApply Juniper's security patches for the affected versions. As an interim measure, consider disabling SRv6 if not required, or implement BGP route filtering to block malformed UPDATE messages.

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= 22.3= 22.4= 23.2= 23.4
Junos Os EvolvedOperating system
Affected:< 21.2= 21.2= 21.4= 22.2= 22.3= 22.4= 23.2= 23.4

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/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 version
    Run 'show version' command or inspect system version in configuration
    Affected if Version matches < 21.2, = 21.2, = 21.4, = 22.2, = 22.3, = 22.4, = 23.2, or = 23.4
  2. Verify SRv6 is enabled
    Run 'show srv6' or check configuration for 'set protocols srv6' statements
    Affected if SRv6 configuration is present and active
  3. Confirm BGP is configured
    Run 'show bgp summary' or check for 'set protocols bgp' configuration
    Affected if BGP is configured and operational
  4. Check if device accepts BGP connections from untrusted sources
    Review BGP peer configuration and access lists under 'set protocols bgp group'
    Affected if BGP peers are reachable from untrusted networks without route filtering

Device is affected if it runs a vulnerable Junos version listed above, has SRv6 enabled, and has BGP configured with external or unprotected peers that could receive malformed UPDATE packets.

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

Apply Juniper's security patches for the affected versions. As an interim measure, consider disabling SRv6 if not required, or implement BGP route filtering to block malformed UPDATE messages.

Recommended fix High confidence

Upgrade to 21.2R3-S9+ / 21.4R3-S10+ / 22.2R3-S5+ / 22.3R3-S4+ / 22.4R3-S3+ / 23.2R2-S2+ / 23.4R2+ (or later supported release) depending on current version branch

  1. 1. Identify the current Junos OS or Junos OS Evolved version installed on the device using 'show version'
  2. 2. Confirm whether SRv6 (Segment Routing over IPv6) is enabled using 'show configuration protocols bgp' and checking for srv6 configuration
  3. 3. If SRv6 is enabled, the device is vulnerable and requires upgrade
  4. 4. Determine the appropriate upgrade path based on current version: for 21.2.x upgrade to 21.2R3-S9 or later, for 21.4.x upgrade to 21.4R3-S10 or later, for 22.2.x upgrade to 22.2R3-S5 or later, for 22.3.x upgrade to 22.3R3-S4 or later, for 22.4.x upgrade to 22.4R3-S3 or later, for 23.2.x upgrade to 23.2R2-S2 or later, for 23.4.x upgrade to 23.4R2 or later
  5. 5. Download the appropriate upgrade package from the Juniper Networks support portal (supportportal.juniper.net)
  6. 6. Upload the upgrade package to the device using 'file copy' or USB transfer
  7. 7. Install the upgrade using 'request system software add <package>' with appropriate options such as 'reboot'
  8. 8. After reboot, verify the new version is installed using 'show version'
Caveat Standard Junos upgrade considerations apply - review release notes for any changes to BGP, SRv6, or routing behavior; 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
  • 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-2025-21593 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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