CVE-2021-0209

Routing-service crash via valid BGP updates

Published Jan 15, 2021 · Updated Sep 17, 2024

Access of an uninitialized pointer in Juniper Networks Junos OS Evolved allows attackers to crash RPD via valid BGP updates. When RPD processes certain valid updates from a configured BGP peer while REGEX is in use, it accesses an uninitialized pointer and writes an rpd.re core file. The peer position and configuration are required; continued delivery extends the routing-service interruption, and RPD must be restarted to recover.

CVSS severity6.5
Medium
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Access of an uninitialized pointer in Juniper Networks Junos OS Evolved allows attackers to crash RPD via valid BGP updates. When RPD processes certain valid updates from a configured BGP peer while REGEX is in use, it accesses an uninitialized pointer and writes an rpd.re core file. The peer position and configuration are required; continued delivery extends the routing-service interruption, and RPD must be restarted to recover.

The record

CVE
CVE-2021-0209
Published
Jan 15, 2021
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-824, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 2021CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=19.4 <19.4R2-S2-EVO
  2. Affected versionversion=20.1 <20.1R1-S2-EVO, 20.1R2-S1-EVO

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=19.4 <19.4R2-S2-EVO; version=20.1 <20.1R1-S2-EVO, 20.1R2-S1-EVO

Published CVSS scores

6.5Juniper Networks, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.7NIST NVDAV:A/AC:M/Au:N/C:N/I:N/A:C

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-824Access of Uninitialized Pointer
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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