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CVE-2021-28510

For certain systems running EOS, a Precision Time Protocol (PTP) packet of a management/signaling message with an invalid Type-Length-Value (TLV) causes the PTP agent to restart. Repeated restarts of the service will make the service unavailable.

Medium5.3Public exploitEPSS 1.0%
Published
Updated
Reserved
Assigned by
Arista

Description

For certain systems running EOS, a Precision Time Protocol (PTP) packet of a management/signaling message with an invalid Type-Length-Value (TLV) causes the PTP agent to restart. Repeated restarts of the service will make the service unavailable.

Public exploit

An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: a proof of concept is public.

Timeline

  1. ID reserved

    By Arista

  2. · 23 months later

    Published

  3. · 2 years later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2021-28510, by who scored it
Scored byCVSSScoreVector
AristaCNA (assigner)3.1Medium5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVDNVD · Modified3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
1.0% · top 37% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: poc · Automatable: yes · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.

Weakness

Affected products

  • Arista Networks · EOS

    • affected 4.22
    • affected 4.27.1 – ≤ 4.27.0
    • affected 4.26.4 – ≤ 4.26.0
    • affected 4.25.6 – ≤ 4.25.0
    • affected 4.24.8 – ≤ 4.24.0
    • affected 4.23.10 – ≤ 4.23.0

What to do

Solution: The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Artista recommends customers move to the latest version of each release that contains all the fixes listed below. CVE-2021-28510 has been fixed in the following releases: 4.27.2 and later releases in the 4.27.x train 4.26.5 and later releases in the 4.26.x train 4.25.7 and later releases in the 4.25.x train 4.24.9 and later releases in the 4.24.x train 4.23.11 and later releases in the 4.23.x train

Solution: Hotfix The following hotfix can be applied to remediate CVE-2021-28510 Note: Installing/uninstalling the SWIX will cause the PTP agent to restart. Version: 1.0 URL:SecurityAdvisory76_CVE-2021-28510_Hotfix.swix SWIX hash: (SHA-512)2b78b8274b7c73083775b0327e13819c655db07e22b80038bb3843002c679a798b53a4638c549a86183e01a835377bf262d27e60020a39516a5d215e2fadb437

Workaround: Install ACL rules to drop PTP packets from untrusted sources. Best practice is to block access to untrusted (non-management) networks.

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .