ARP policing bypass via daemon race
Published Jul 15, 2021 · Updated Sep 17, 2024
A TOCTOU race in Juniper Networks Junos OS allows adjacent unauthenticated attackers to bypass user-defined ARP policing on AE units. A race between the DCD and dfwd daemons replaces the configured user policer with the default ARP policer instead of applying the intended rate limit. Exploitation requires a user-defined ARP policer on an Aggregated Ethernet unit and permits traffic to evade that limit, potentially interrupting service.
Summary
What happened
A TOCTOU race in Juniper Networks Junos OS allows adjacent unauthenticated attackers to bypass user-defined ARP policing on AE units. A race between the DCD and dfwd daemons replaces the configured user policer with the default ARP policer instead of applying the intended rate limit. Exploitation requires a user-defined ARP policer on an Aggregated Ethernet unit and permits traffic to evade that limit, potentially interrupting service.
The record
- CVE
- CVE-2021-0289
- Published
- Jul 15, 2021
- Updated
- Sep 17, 2024
- Vendor
- Juniper Networks
- Product
- Junos OS
- Classifications
- CWE-367, T1498
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 15, 2021CVE publishedPublication date reported by the CVE source.
- Sep 17, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=15.1 <15.1R7-S10 changes=[{"at":"15.1F1","status":"affected"}]
- Affected versionversion=16.1R1 <16.1*
- Affected versionversion=16.2R1 <16.2*
- Affected versionversion=17.1R1 <17.1*
- Affected versionversion=17.2R1 <17.2*
- Affected versionversion=17.3R1 <17.3*
- Affected versionversion=17.4R1 <17.4*
- Affected versionversion=18.1R1 <18.1*
- Affected versionversion=18.2R1 <18.2*
- Affected versionversion=18.3R1 <18.3*
- Affected versionversion=18.4 <18.4R2-S9, 18.4R3-S9
- Affected versionversion=18.4 <18.4R2-S9, 18.4R3-S9 changes=[{"at":"18.4R1","status":"affected"}]
- Affected versionversion=19.4 <19.4R3-S3
- Affected versionversion=20.1 <20.1R3
- Affected versionversion=20.2 <20.2R3-S2
- Affected versionversion=20.3R1 <20.3*
- Affected versionversion=20.4 <20.4R3
- Affected versionversion=21.1 <21.1R2
- Affected versionversion=5.6R1 <5.6*
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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