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Junos Os EvolvedOperating system · Juniper

CVE-2026-33794

MEDIUM · 5.9 CVSS v3.1 Published 2026-07-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 6 weeks old

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 Check for Unusual or Exceptional Conditions vulnerability in the advanced forwarding toolkit (evo-aftmand) of Juniper Networks Junos OS Evolved on PTX Series allows an unauthenticated network-based attacker generating continuous routing updates, resulting in unilist ECMP routes, to crash the evo-aftmand process on the PFE, leading to a Denial-of-Service (DoS). The conditions required for successful exploitation are based on a sequence of events that are outside an attacker's direct control. Unified list (unilist) ECMP routes are a specific ECMP behavior where multiple equal-cost routes share a single logical next-hop list entry. The router treats them as one route with multiple next hops and load balances traffic across that unified list. Due to an issue processing unilist ECMP routing updates, internal state corruption may occur, especially in large-scale ECMP unilist deployments, leading to the evo-aftmand process crashing, resulting in an evo-aftmand-bx core. Manual intervention is required to recover by rebooting the system or restarting the FPC. This issue affects Junos OS Evolved on PTX : * from 24.4R2-EVO before 24.4R2-S3-EVO; * from 25.2 before 25.2R2-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

Improper check for unusual conditions in evo-aftmand when processing unilist ECMP routing updates causes internal state corruption, leading to evo-aftmand process crash and DoS on PTX Series routers.

MitigationApply vendor patches (24.4R2-S3-EVO or later, or 25.2R2-EVO or later) to fix the improper check in the advanced forwarding toolkit; until patched, monitor for evo-aftmand crashes and plan maintenance windows for recovery.

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
Junos Os EvolvedOperating system
Affected:= 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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/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. Identify the Junos Evolved version
    Run 'show version' or 'request system version' on the device
    Affected if Version is exactly 24.4 or 25.2 (or falls within these specific version branches if ranges are denoted by =)
  2. Confirm the device is a PTX Series router
    Run 'show chassis hardware' or 'show system information' to identify the hardware model
    Affected if The router is a PTX Series device (PTX5000, PTX3000, PTX1000, PTX10008, etc.)
  3. Verify ECMP with unilist configuration is in use
    Run 'show configuration protocols bgp' or 'show configuration protocols isis' and look for 'multipath' and 'unilist' configuration under the appropriate protocol hierarchy
    Affected if ECMP is configured with the unilist option (e.g., 'set protocols bgp group <name> multipath unicast' with unilist behavior)
  4. Monitor for evo-aftmand process crashes
    Run 'show system processes' or check '/var/log/messages' for recent evo-aftmand crash events using 'show log messages | match aftmand'
    Affected if The evo-aftmand process has crashed or is experiencing instability
  5. Check for ECMP-related routing state corruption
    Run 'show route summary' or 'show route table' and compare ECMP next-hop counts for affected prefixes; look for inconsistent or fluctuating path counts
    Affected if ECMP routes show unexpected state changes or the routing table exhibits corruption symptoms

The device is affected if it runs Junos Evolved 24.4 or 25.2 on PTX Series hardware with ECMP unilist configuration, and exhibits evo-aftmand crashes or routing state anomalies.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor patches (24.4R2-S3-EVO or later, or 25.2R2-EVO or later) to fix the improper check in the advanced forwarding toolkit; until patched, monitor for evo-aftmand crashes and plan maintenance windows for recovery.

Recommended fix High confidence

24.4R2-S3-EVO or 25.2R2-EVO (depending on which version branch you are on)

  1. 1. Identify the current Junos OS Evolved version running on the PTX Series device using 'show version' command
  2. 2. If running a version in the range 24.4R2-EVO (or later) but before 24.4R2-S3-EVO, plan upgrade to 24.4R2-S3-EVO or later
  3. 3. If running a version in the range 25.2 (or later) but before 25.2R2-EVO, plan upgrade to 25.2R2-EVO or later
  4. 4. Schedule a maintenance window as the upgrade will require a system reboot
  5. 5. Before upgrading, backup the current configuration using 'request system configuration backup'
  6. 6. Download the appropriate fixed Junos OS Evolved image from Juniper Networks support portal
  7. 7. Install the upgrade using 'request system software add <package-name>' followed by 'request system reboot'
  8. 8. After reboot, verify the new version is running with 'show version'
Caveat Standard Junos OS upgrade precautions apply - review release notes for any changes to features or configuration commands used in your deployment

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

Fix this in Junos Os Evolved Scoped from the published advisory
  • Consultation12.0 h
  • Implementation24.0 h
  • Testing20.0 h
  • Review / QA8.0 h
64.0 hours of engineering $11,160
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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-2026-33794 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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