CVE-2026-121288 (CVSS 8.1)

Description

An unauthenticated attacker on an adjacent network segment can bypass MD5 authentication and have unauthorized RIP route updates accepted by the device. Successful exploitation requires that RIPv2 MD5 authentication is configured on the affected interface. An attacker who can inject crafted RIPv2 packets could cause the device to install routes that redirect network traffic through attacker-controlled paths, create routing loops, or blackhole traffic, disrupting network connectivity.

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CVSS v3.1 Score

8.1

HIGH

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

EPSS — Exploit Prediction

0.0024

Probability of exploitation

0.15%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-303 CWE-303

References

Other References

https://www.arista.com/en/support/advisories-notices/security-advisory/25043-security-advisory-0221

Frequently Asked Questions

What is CVE-2026-121288? +

An unauthenticated attacker on an adjacent network segment can bypass MD5 authentication and have unauthorized RIP route updates accepted by the device. Successful exploitation requires that RIPv2 MD5 authentication is configured on the affected interface. An attacker who can inject crafted RIPv2 packets could cause the device to install routes that redirect network traffic through attacker-controlled paths, create routing loops, or blackhole traffic, disrupting network connectivity. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-121288? +

CVE-2026-121288 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0024, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-121288? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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