CVE-2020-1637Network attack vector

Unauthorized network access via UAC range misinterpretation

Published Apr 8, 2020 · Updated Sep 16, 2024

Authentication bypass in affected Junos OS 12.3X48 through 19.4 branches on SRX Series allows remote attackers to access UAC-protected resources. When an Infranet Controller defines a protected IP range as start and end addresses rather than as an address and netmask, the Junos OS Enforcer applies the UAC policy incorrectly. Reachability requires an SRX device operating as an Enforcer with the default-disabled CLI settings enabled, and the consequence is limited to resources the applicable UAC policy should deny.

CVSS severity7.2
High
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in affected Junos OS 12.3X48 through 19.4 branches on SRX Series allows remote attackers to access UAC-protected resources. When an Infranet Controller defines a protected IP range as start and end addresses rather than as an address and netmask, the Junos OS Enforcer applies the UAC policy incorrectly. Reachability requires an SRX device operating as an Enforcer with the default-disabled CLI settings enabled, and the consequence is limited to resources the applicable UAC policy should deny.

The record

CVE
CVE-2020-1637
Published
Apr 8, 2020
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-288, CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 8, 2020CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=12.3X48 <12.3X48-D100
  2. Affected versionversion=15.1X49 <15.1X49-D210
  3. Affected versionversion=17.3 <17.3R2-S5, 17.3R3-S8
  4. Affected versionversion=17.4 <17.4R2-S9, 17.4R3-S1
  5. Affected versionversion=18.1 <18.1R3-S10
  6. Affected versionversion=18.2 <18.2R2-S7, 18.2R3-S3
  7. Affected versionversion=18.3 <18.3R1-S7, 18.3R3-S2
  8. Affected versionversion=18.4 <18.4R1-S6, 18.4R2-S4, 18.4R3-S1
  9. Affected versionversion=19.1 <19.1R1-S4, 19.1R2-S1, 19.1R3
  10. Affected versionversion=19.2 <19.2R1-S3, 19.2R2
  11. Affected versionversion=19.3 <19.3R2-S1, 19.3R3
  12. Affected versionversion=19.4 <19.4R1-S1, 19.4R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=12.3X48 <12.3X48-D100; version=15.1X49 <15.1X49-D210; version=17.3 <17.3R2-S5, 17.3R3-S8; version=17.4 <17.4R2-S9, 17.4R3-S1; version=18.1 <18.1R3-S10; version=18.2 <18.2R2-S7, 18.2R3-S3; version=18.3 <18.3R1-S7, 18.3R3-S2; version=18.4 <18.4R1-S6, 18.4R2-S4, 18.4R3-S1; version=19.1 <19.1R1-S4, 19.1R2-S1, 19.1R3; version=19.2 <19.2R1-S3, 19.2R2; version=19.3 <19.3R2-S1, 19.3R3; version=19.4 <19.4R1-S1, 19.4R2

Published CVSS scores

5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
7.2Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-288Authentication Bypass Using an Alternate Path or Channel
CWE-287Improper Authentication
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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