CVE-2026-121291VulnerabilityPublished 10 Nov 2026

A crafted Error Report can leave EOS stuck believing that a cache reset is in progress, preventing ROA publication

Source GCVE Database

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Authoritative record:CVE-2026-121291· High 8.2

Not known to be exploited · CVSS 8.2 High.

Data as of 10 Nov 2026, 23:19 UTC

CVSS 3.1 base score

8.2High

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	8.2
CNA (Arista)	CVSS 4.0	8.3

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

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

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
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: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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.

ghsa-r4g2-mmcv-4w88

What to do

Affected software

Product	Affected	Fixed in
Arista NetworksEOS	Affected >=4.36.0F <=4.36.2F >=4.35.0F <=4.35.6M =4.37.0F	Fixed in–

AI-suggested

Until a fix is available, operators should monitor for vendor updates and consider operational workarounds if possible.

Description

A vulnerability identified as CVE-2026-121291 involves a crafted Error Report that can cause the EOS system to incorrectly remain in a state where it believes a cache reset is ongoing. This condition prevents the publication of ROAs (Route Origin Authorizations), disrupts withdrawal reconciliation, and halts BGP origin-validation updates.

Impact

The vulnerability prevents EOS from completing cache resets, which in turn stops ROA publication and BGP origin-validation updates. This disruption can impair the integrity of routing information and delay withdrawal reconciliation, potentially leading to routing inconsistencies or failures in origin validation processes. There is no confidentiality impact reported. Availability impact is low but present due to the system being stuck in an incorrect state.

Summary

CVE-2026-121291 describes a vulnerability in EOS where a specially crafted Error Report can cause the system to remain stuck in a cache reset state. This persistent state blocks critical functions including ROA publication, withdrawal reconciliation, and BGP origin-validation updates, potentially impacting network routing security and operations. The vulnerability has a CVSS 3.1 score of 8.2, indicating high severity, with network attack vector, low attack complexity, no privileges or user interaction required, unchanged scope, no confidentiality impact, high integrity impact, and low availability impact.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Nov 2026, 23:19 UTC

WeaknessesCWE-696

Technical details

References

Community reviews

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