Threat Intelligence Report — CVE-2026-73442

Executive Summary

CVE-2026-73442 is a cleartext credential disclosure vulnerability (CWE-532) affecting Arista EOS platforms running VRRP (Virtual Router Redundancy Protocol) with authentication enabled. When VRRP peer authentication is configured, the peer device's VRRP authentication credentials are written to agent trace logs in cleartext, allowing an authenticated local user with sufficient privileges to read those logs — or any system receiving forwarded log output — and recover the peer's VRRP credentials. The impact is limited but meaningful: an attacker who cannot reach the VRRP network segment can still capture credentials through log access, obtaining a lateral pivot into the first-hop redundancy protocol trust domain. The CVSS base score is 3.0 (Low), reflecting the adjacent network vector, high attack complexity, low privileges required, and confidentiality-only impact.

Technical Analysis

The vulnerability class here is insertion of sensitive information into a log file (CWE-532). VRRP supports authentication between virtual router peers so that rogue devices cannot inject themselves into a VRRP group and hijack the virtual IP/MAC. In affected Arista EOS builds, when agent trace logging is enabled, the VRRP subsystem emits diagnostic trace output that includes the authentication credentials exchanged with, or configured for, the peer device — and it emits them in cleartext rather than redacted or hashed.

Because the credentials land in a log stream rather than on the wire, the exposure surface is fundamentally different from a normal network credential sniff:

• On-box log access: An authenticated user with sufficient privileges to view agent trace logs can read the peer VRRP authentication string directly.
• Off-box log forwarding: Any remote log receiver (syslog collector, SIEM, log forwarder) configured to accept forwarded output from the switch likewise receives the cleartext credential and can be read by anyone with access to that downstream system.

The CVSS vector AV:A (Adjacent) reflects that the attacker must be positioned somewhere on the switch or its log-management plane rather than purely remote over the internet. AC:H (High) reflects preconditions — VRRP authentication must be configured, trace logging must be enabled or have run, and the attacker must have log-read privileges. PR:L (Low) reflects that the reading user needs only ordinary authenticated privileges on the device. S:C (Scope Changed) captures that the credential obtained on the switch grants access to a different security authority: the VRRP peer relationship and the segment on which VRRP operates. C:L reflects low confidentiality impact; I:N/A:N reflect no integrity or availability impact.

Important accuracy note: The source description does not identify specific function names, log file paths, CLI command syntax, or the exact storage format of the credential. No public PoC, Nuclei template, or exploit code is available. Any additional implementation-level detail beyond the above would be speculative and is deliberately omitted.

Exploitation Scenarios

The attack chain below is inferred from the vulnerability class (cleartext credential logging) and the NVD description. No public PoC exists.

Step 1 — Reconnaissance / target identification. The attacker identifies an Arista EOS device running VRRP with authentication enabled. This is an internal-first vector: the attacker must already have some foothold — an authenticated account on the switch, or access to a downstream log-collection system that receives the switch's forwarded logs. Publicly exposed management interfaces on internet-facing EOS switches would be the entry point for the AV:A positioning.

Step 2 — Triggering the flaw class. A cleartext-logging flaw of this class does not require the attacker to send a crafted packet. The sensitive data is written to the log as a byproduct of normal operation: the VRRP agent emits trace output during routine VRRP processing, and that output includes the peer's authentication credentials verbatim. For on-box access, the attacker issues the privileged log-viewing operation to read agent trace logs. For off-box access, the attacker reads the forwarded log stream on the collector.

Step 3 — Credential extraction. The attacker greps/parses the trace log for the VRRP authentication credential (as emitted in cleartext). No payload or exploit primitive is required — this is a passive disclosure. The credential enables the attacker to authenticate to, or impersonate participation in, the VRRP group.

Step 4 — Post-exploitation impact. With the recovered peer VRRP credentials, the attacker can potentially participate in the VRRP group from the segment on which VRRP runs — a segment the attacker previously could not reach. This defeats the integrity purpose of VRRP authentication. The immediate consequence is limited confidentiality exposure (attacker obtains a credential), which is why the score is low — but it is a meaningful enabler for first-hop / gateway-hijack style follow-on activity if combined with network access. No integrity or availability impact is scored because the disclosure itself is read-only.

No public exploit code, Nuclei template, or in-the-wild exploitation is known. No CISA KEV entry exists.

Impact Assessment

Business impact. The credential exposed is a VRRP authentication secret — a trust anchor for first-hop redundancy. Leakage into logs (especially SIEM/log-platform copies retained for months) creates a long-lived exposure: even after the switch is patched, previously forwarded cleartext credentials may persist in downstream log storage. Organizations subject to PCI DSS, HIPAA, or similar regimes face a credential-handling/audit finding, since cleartext secrets in logs violate standard data-protection expectations.

Affected systems. Arista EOS platforms with VRRP authentication enabled and agent trace logging active. The exact affected version ranges were not published in the source data provided.

Blast radius. Two populations: (1) the switch itself, read by any sufficiently privileged local user; (2) every system receiving forwarded log output (syslog servers, SIEM, cloud log pipelines). The latter dramatically increases the number of people and systems that can reach the plaintext credential.

CVSS subscores. Base 3.0 — AV:A, AC:H, PR:L, UI:N, S:C, C:L, I:N, A:N. Confidentiality:Low only. Scope:Changed is notable — the credential obtained in the switch's log scope is usable against the VRRP network scope, not just the switch. EPSS is not yet scored by FIRST.org; no value should be assumed.

Detection Guidance

Detection must focus on log-read activity by unauthorized/low-privilege accounts, on forwarded log content containing VRRP auth strings, and on credential-harvesting patterns against EOS logs. Because the flaw is a logging defect rather than a network exploit, network IDS coverage is limited to detecting anomalous log-forwarding or harvesting traffic.

Sigma Rule

title: Arista EOS VRRP Cleartext Credential Access in Agent Trace Logs
id: 7c8e1a44-4e2b-4f9a-9d3e-arista73442
status: experimental
description: Detects privileged access to Arista EOS agent trace logs where VRRP authentication credentials may be written in cleartext (CVE-2026-73442).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-73442
author: valtersit.com Threat Intelligence
date: 2026/01/01
tags:
  - attack.credential_access
  - attack.t1552.001
logsource:
  product: arista
  service: eos
detection:
  selection_cmd:
    - 'show agent.*trace'
    - 'show logging.*trace'
    - 'more.*agent.*trace'
    - 'grep.*vrrp'
  selection_vrrp:
    - '*VRRP*auth*'
    - '*vrrp.*cleartext*'
  condition: selection_cmd
falsepositives:
  - Authorized administrators performing routine diagnostics during maintenance windows
level: medium

YARA Rule

rule CVE_2026_73442_Arista_VRRP_Cleartext_Credential_Leak
{
    meta:
        description = "Detects Arista EOS agent trace logs containing VRRP authentication credentials in cleartext"
        author = "valtersit.com Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-73442"
        cve = "CVE-2026-73442"
        date = "2026-01-01"

    strings:
        $vrrp = "VRRP" nocase
        $auth = "auth" nocase
        $trace = "trace" nocase
        $agent = "agent" nocase
        $cleartext_hint1 = "authentication" nocase
        $cleartext_hint2 = "peer" nocase

    condition:
        filesize < 50MB and
        $vrrp and $auth and $agent and ($trace or $cleartext_hint1 or $cleartext_hint2)
}

Note: The rule is intentionally heuristic. The exact log-line format was not published, so the rule keys on the co-occurrence of VRRP, auth, and agent/trace tokens in log artifacts rather than a fabricated string.

Suricata IDS Rule

alert tcp any any -> any 514 ( \
  msg:"CVE-2026-73442 Arista EOS VRRP cleartext credential in forwarded syslog"; \
  flow:established,to_server; \
  content:"VRRP"; nocase; \
  content:"auth"; nocase; \
  content:"peer"; nocase; \
  classtype:attempted-recon; \
  reference:cve,2026-73442; \
  sid:10073442; rev:1; )

Rationale: Arista EOS forwards logs to syslog collectors commonly over TCP/514. Detection keys on VRRP auth context appearing in forwarded log payloads. If log forwarding uses TLS, this rule will not fire — deploy content inspection at the collector instead.

Elastic Detection

process where event.type in ("start", "process_started") and
process.command_line != null and
(
  process.command_line : "*agent*trace*" or
  process.command_line : "*show logging*trace*"
) and
process.command_line : "*vrrp*"

Rationale: Detects command-line invocations that combine agent-trace log access with VRRP context. Pair with a user-context filter to flag non-admin/low-privilege accounts.

Splunk SPL Query

index=arista sourcetype=eos_log OR sourcetype=syslog
("agent" AND "trace" AND "VRRP")
OR ("VRRP" AND "auth" AND "peer")
| stats count min(_time) as first_seen max(_time) as last_seen
    values(host) as hosts values(user) as users by src, dest
| where count > 0
| convert ctime(first_seen) ctime(last_seen)

Use case: Surface hosts/log streams where VRRP authentication context is appearing in trace output, and identify which users/hosts touched them.

Wazuh OSSEC Rule

<group name="arista,eos,cve-2026-73442,">
  <rule id="100442" level="10">
    <decoded_as>syslog</decoded_as>
    <match>VRRP</match>
    <match>auth</match>
    <description>CVE-2026-73442: Possible VRRP authentication credential in Arista EOS log/trace output</description>
    <mitre>
      <id>T1552.001</id>
    </mitre>
  </rule>

  <rule id="100443" level="8">
    <decoded_as>syslog</decoded_as>
    <regex>agent.*trace.*VRRP</regex>
    <description>CVE-2026-73442: VRRP context observed in Arista EOS agent trace logging</description>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED). No vendor patch, advisory, or workaround evidence exists in any tracked source. Do not assume a fixed version exists.

1) Immediate mitigations (compensating controls).

• Disable or restrict agent trace logging on devices running VRRP with authentication, unless actively troubleshooting in a controlled window. Trace logging is the sink for the cleartext credential.
• Restrict log-read privileges. Apply least privilege so that only a minimal set of administrators can view agent trace logs.
• Protect forwarded log streams. Encrypt log forwarding (TLS) and strictly control access to syslog/SIEM collectors. Assume any collector that already received forwarded logs may hold plaintext credentials.
• Rotate VRRP authentication credentials on all devices where trace logging may have run, since previously logged credentials must be treated as compromised.
• Review and purge historical log stores for VRRP auth strings; if found, treat as a credential-disclosure incident.

2) Patch / upgrade steps.

• Monitor the vendor security advisory channel for an EOS release addressing CVE-2026-73442.
• When a fixed release is published, validate the exact affected-to-fixed version mapping before scheduling upgrades.
• No workaround is published; interim risk reduction depends entirely on the compensating controls above.

3) Long-term hardening.

• Eliminate cleartext secret logging at the platform level wherever possible; prefer mechanisms that never emit secrets to logs.
• Enforce structured log scrubbing/redaction at the collector with regex pipelines for known secret patterns.
• Adopt least-privilege log access as a standing control, not a one-time fix.
• Include log-content secret scanning in continuous controls (a "secrets in logs" detection class).

References

1. NVD — CVE-2026-73442: https://nvd.nist.gov/vuln/detail/CVE-2026-73442
2. CWE-532 — Insertion of Sensitive Information into Log File: https://cwe.mitre.org/data/definitions/532.html
3. MITRE ATT&CK T1552.001 — Unsecured Credentials: Credentials In Files: https://attack.mitre.org/techniques/T1552/001/
4. FIRST.org EPSS — model overview (CVE-2026-73442 not yet scored): https://www.first.org/epss/
5. Arista Security Advisories portal (monitor for an EOS advisory on this CVE): https://www.arista.com/en/support/advisories-notices

Threat actor / exploit-in-the-wild evidence: None. CVE-2026-73442 is not in CISA KEV. No public PoC, Nuclei template, or exploit code is available. No known campaigns observed. The report does not assume exploitation activity.