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🛡️ CVE-2026-33794 — junos-os-evolved

🟡 CVSS 5.9 — Medium ✅ No Known Exploit CWE-754 NVD
5.9
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-33794 is classified as CWE-754: Improper Check for Unusual or Exceptional Conditions. The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

Affected software

CVE-2026-33794 is recorded against 1 package.

  • junos-os-evolved

Timeline and source

Published on 9 July 2026 and last revised on 13 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

supportportal.juniper.net

Other advisories for this package

junos-os-evolved has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-754: Improper Check for Unusual or Exceptional Conditions) in other software:

Details

Severity MEDIUM
CVSS Score 5.9
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-754
Public Exploit ✅ No
Source NVD
Published 2026-07-09
Updated 2026-08-20
Modified 2026-07-13
Fix URL N/A

Affected Packages

Software From version Fixed in
junos-os-evolved — —

References

Mitigation, Vendor Advisory https://supportportal.juniper.net/JSA110073

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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