CVE-2021-0297Network attack vector

Unauthorized routing sessions via missing peer MD5

Published Oct 19, 2021 · Updated Sep 17, 2024

Improper TCP MD5 authentication in Juniper Networks Junos OS Evolved allows remote attackers to establish unauthorized BGP or LDP sessions. The TCP authentication path accepts a peer when the local session requires MD5 but the peer sends no TCP MD5 authentication, instead of rejecting the connection. The gate is an MD5-protected BGP or LDP configuration, and an untrusted peer can gain routing-session access without possessing the configured secret.

CVSS severity6.5
Medium
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper TCP MD5 authentication in Juniper Networks Junos OS Evolved allows remote attackers to establish unauthorized BGP or LDP sessions. The TCP authentication path accepts a peer when the local session requires MD5 but the peer sends no TCP MD5 authentication, instead of rejecting the connection. The gate is an MD5-protected BGP or LDP configuration, and an untrusted peer can gain routing-session access without possessing the configured secret.

The record

CVE
CVE-2021-0297
Published
Oct 19, 2021
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-755, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 19, 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=20.4 <20.4R2-EVO
  2. Affected versionversion=21.1 <21.1R2-EVO
  3. Affected versionversion=unspecified <20.3R2-S1-EVO

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=20.4 <20.4R2-EVO; version=21.1 <21.1R2-EVO; version=unspecified <20.3R2-S1-EVO

Published CVSS scores

6.5Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1190Exploit Public-Facing Application

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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