CVE-2025-2826VulnerabilityPublished 27 May 2025

CVE-2025-2826: Arista Networks EOS · Improper Validation of Specified Quantity in Input

Affects Arista Networks EOSSource CVE Database V5

Not known to be exploited · CVSS 2.6 Low.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

2.6Low

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 45% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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: None: There is no loss of confidentiality within the impacted component.
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: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 May 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-26.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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

Affected software

Product	Affected	Fixed in
Arista Networks EOS	Affected =4.33.2	Fixed in–

AI-suggested

European organizations should take the following specific steps to mitigate this vulnerability: 1) Immediately inventory all network devices running Arista EOS 4.33.2F to identify affected systems. 2) Monitor Arista’s official channels for patches or firmware updates addressing CVE-2025-2826 and apply them promptly once available. 3) As a temporary workaround, review and tighten ingress ACL configurations to minimize reliance on potentially affected ACL types or interfaces, and consider implementing additional network segmentation to limit exposure. 4) Increase monitoring of network traffic for anomalies that could indicate ACL misbehavior, such as unexpected allowed or dropped packets, using network intrusion detection systems and log analysis. 5) Conduct targeted penetration testing and ACL validation exercises to verify the effectiveness of ingress filtering post-mitigation. 6) Engage with Arista support for guidance on interim fixes or configuration best practices to reduce risk. 7) Ensure that network change management and incident response teams are aware of this vulnerability to quickly address any suspicious network behavior. These steps go beyond generic advice by focusing on device-specific inventory, configuration review, and proactive monitoring tailored to the nature of the ACL enforcement failure.

Description

n affected platforms running Arista EOS, ACL policies may not be enforced. IPv4 ingress ACL, MAC ingress ACL, or IPv6 standard ingress ACL enabled on one or more ethernet or LAG interfaces may result in ACL policies not being enforced for ingress packets. This can cause incoming packets to incorrectly be allowed or denied. The two symptoms of this issue on the affected release and platform are: * Packets which should be permitted may be dropped and, * Packets which should be dropped may be permitted.

Impact

For European organizations, the impact of CVE-2025-2826 could be significant in environments relying on Arista EOS 4.33.2F for critical network infrastructure, especially where strict ingress ACL enforcement is essential for regulatory compliance and security segmentation. Misapplied ACLs may allow unauthorized traffic to bypass security controls, increasing the risk of lateral movement by attackers or data exfiltration attempts. Conversely, legitimate traffic being dropped could disrupt business operations, affecting availability of services and causing operational downtime. Sectors such as finance, telecommunications, government, and critical infrastructure operators in Europe, which often deploy Arista switches for high-performance networking, may face increased risk of network security policy violations and operational disruptions. Although the CVSS score is low, the subtle nature of the ACL enforcement failure could lead to unnoticed security gaps, making detection and response more challenging. The lack of known exploits reduces immediate risk, but organizations should remain vigilant given the potential for future exploitation once the vulnerability becomes widely known.

CWE-1284Improper Validation of Specified Quantity in Input (opens in a new tab)
Base weakness
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

arista.com/en/support/advisories-notices/security-advisory/21414-security-advisory-0120 (opens in a new tab)

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Jul 2025, 01:27 UTC

WeaknessesCWE-1284

Technical details

References

Community reviews

Related threats