VulnerabilityPublished 10 Nov 2026

CVE-2026-120983: Arista Networks EOS · Improper Access Control

Affects Arista Networks EOSSource CVE Database V5

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Not known to be exploited · CVSS 7.6 High : upgrade to 4.33.0F soon.

Data as of 10 Nov 2026, 20:32 UTC

CVSS 3.1 base score

7.6High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (Arista)	CVSS 3.1	7.6
CNA (Arista)	CVSS 4.0	6.1

Patch: Available – fixed in 4.33.0F

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Arista Networks EOS to 4.33.0F.

Affected software

Product	Affected	Fixed in
Arista NetworksEOS	Affected >=1.0.0 <4.33.0F >=4.33.0F <=4.33.9M >=4.34.0F <=4.34.7M >=4.35.0F <=4.35.5M >=4.36.0F <=4.36.1F	Fixed in 4.33.0F

AI-suggested

A fix is available in Arista EOS version 4.33.0F and later. Users should upgrade affected EOS platforms to version 4.33.0F or newer to remediate this vulnerability. There are no indications that temporary workarounds or mitigations are provided or required beyond applying the official fix.

Description

CVE-2026-120983 is an improper access control vulnerability in Arista Networks EOS affecting configurations where 802.1x is set to multi-host authenticated mode alongside Policy Based Routing (PBR). This flaw allows traffic from unauthenticated hosts to be forwarded according to PBR policies, potentially granting unauthorized network access. Additionally, Layer 2 and Layer 3 control packets from unauthenticated hosts may be copied to the device CPU. The vulnerability is rated high severity with a CVSS score of 7.6 and affects multiple EOS versions prior to 4.33.0F, which contains the fix.

Impact

The vulnerability allows unauthenticated hosts to bypass 802.1x authentication controls when PBR is configured, enabling unauthorized access to networks defined by PBR policies. This can lead to unauthorized data exposure (high confidentiality impact). Additionally, the copying of Layer 2 and Layer 3 control packets from unauthenticated hosts to the CPU may affect device performance or stability (low availability impact). Integrity impact is low as the vulnerability does not directly allow modification of data or configurations.

Summary

This vulnerability in Arista EOS arises when 802.1x multi-host authentication is combined with Policy Based Routing. Due to improper access control (CWE-284), unauthenticated hosts can have their traffic forwarded to destinations specified in PBR policies, bypassing intended authentication restrictions. Furthermore, control packets at Layer 2 and Layer 3 from these unauthenticated hosts may be copied to the CPU, potentially impacting device processing. The issue affects EOS versions from 1.0.0 up to but not including 4.33.0F, as well as certain later versions up to 4.36.1F. The vendor fixed the vulnerability starting with version 4.33.0F. The CVSS v3.1 score of 7.6 reflects high impact on confidentiality, low impact on integrity, and low impact on availability, with attack vector requiring adjacent network access and no privileges or user interaction needed.

CWE-284Improper Access Control (opens in a new tab)
Pillar weaknessCWE Top 25 (2025): #19OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Operation
Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
Architecture and Design · Separation of Privilege
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
OWASP Cheat Sheets
Docker Security (opens in a new tab)
Third Party Javascript Management (opens in a new tab)
Virtual Patching (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V1.4.4 (opens in a new tab)
V1.4.5 (opens in a new tab)
V1.10.1 (opens in a new tab)
Attack patterns
Embedding Scripts within Scripts (opens in a new tab)
Modification of Windows Service Configuration (opens in a new tab)
Malicious Root Certificate (opens in a new tab)
Intent Spoof (opens in a new tab)
WebView Exposure (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

arista.com/en/support/advisories-notices/security-advisory/25037-security-advisory-0215 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Nov 2026, 20:32 UTC

WeaknessesCWE-284

Technical details

References

Community reviews

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