CVE Intelligence
Medium Logic error

CVE-2026-33794 — Junos OS Evolved: PTX Series: Receipt of repeated ECMP routing updates results in PFE crash

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.

Published Jul 9, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: juniper

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.4% (30-day exploitation probability)+5
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.41%
ahead of 33% of scored CVEs · Oct 16, 2026
Affects
Juniper Networks
Junos Os Evolved
CVSS base
5.9
Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Juniper Networks Junos Os Evolved).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the documented mitigations until a definitive fix is available.
  4. Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Juniper Networks Junos Os Evolved version 24.4-r2version 24.4-r2-s1version 24.4-r2-s2version 25.2version 25.2-r1version 25.2-r1-s1version 25.2-r1-s2 Vulnerable NIST National Vulnerability Database
Juniper Networks Junos Os Evolved ≥ 24.4R2-EVO and < 24.4R2-S3-EVO≥ 25.2 and < 25.2R2, 25.2R2-EVO Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.2 CVSS 4.0 High — — sirt@juniper.net via NIST National Vulnerability Database
8.2 CVSS 4.0 High — — juniper via CVE Program (cve.org) e CISA ADP
5.9 CVSS 3.1 Medium 2.2 3.6 sirt@juniper.net via NIST National Vulnerability Database
5.9 CVSS 3.1 Medium — — juniper via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: sirt@juniper.net)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-754 · Improper Check for Unusual or Exceptional Conditions

Other CVEs with this weakness →

EPSS over time FIRST

Oct 15, 2026 → Oct 16, 2026 · 2 reading(s) · max 0.41%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · juniper networks/junos os evolved
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • Fix documented
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVSS changed · 5.9
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Jul 9, 2026 · juniper

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

Elsewhere on this site

Juniper Networks
every CVE for this vendor
Logic error
same class
CWE-754
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-101983 Junos OS and Junos OS Evolved: An attacker causes remote code execution when J-Web virtual-domain is configured 2d
  • CVE-2026-101982 Junos OS and Junos OS Evolved: A EVPN peer causes an rpd crash or root-level compromise when EVPN-VPWS is used 2d
  • CVE-2026-101976 Junos OS and Junos OS Evolved: In a non-4byte-AS scenario a specific BGP update causes an rpd crash 2d
  • CVE-2026-101979 Junos OS and Junos OS Evolved: A network attacker causes root-level code execution or denial of service when SNMP and AAA are enabled 2d
  • CVE-2026-101981 Junos OS and Junos OS Evolved: An adjacent LDP peer causes routing-engine compromise when LDP is enabled 2d
  • CVE-2026-101964 Junos OS and Junos OS Evolved: An attacker can cause an rpd crash via a crafted LDP message 2d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-33794 is "Junos OS Evolved: PTX Series: Receipt of repeated ECMP routing updates results in PFE crash", rated Medium. It affects Junos Os Evolved (Juniper Networks); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.9 describes technical severity. EPSS 0.41% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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