CVSS 4.0
8.3 highCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:L/SA:NCVE-2026-121291 Security Advisory 0222
High (8.3) in arista networks eos. EPSS 0.4% estimated probability of exploitation activity in the next 30 days.
On this page
A crafted Error Report can leave EOS stuck believing that a cache reset is in progress, preventing ROA publication, withdrawal reconciliation, and BGP origin-validation updates.
Severity
CVSS 3.1
8.2 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L- EPSS
- 0.4% estimated probability of exploitation activity in the next 30 days; 36th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: yes · Technical impact: partial, assessed 2026-11-13. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-696 Incorrect Behavior Order
- Published
- Modified
- Assigned by
- Arista (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
Ask an AI about this CVE
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Explain CVE-2026-121291 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-121291?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-121291?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-121291 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
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Affected
- arista networks:eos
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| Arista Networks EOS | 4.37.0F |
| Arista Networks EOS | from 4.36.0F through 4.36.2F |
| Arista Networks EOS | from 4.35.0F through 4.35.6M |
Attack patterns (CAPEC)
- CAPEC-463 Padding Oracle Crypto Attack Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.