CVE-2021-31377

Routing-service interruption via incorrectly permissioned file

Published Oct 19, 2021 · Updated Sep 16, 2024

Incorrect file permissions in affected Juniper Networks Junos OS releases allow local users to crash and restart RPD. Juniper identifies an incorrectly permissioned filesystem file but does not disclose the file, its permissions, or the operation that makes RPD terminate. Local authenticated access is required, and repeated triggering sustains routing-service interruption through recurring RPD restarts.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect file permissions in affected Juniper Networks Junos OS releases allow local users to crash and restart RPD. Juniper identifies an incorrectly permissioned filesystem file but does not disclose the file, its permissions, or the operation that makes RPD terminate. Local authenticated access is required, and repeated triggering sustains routing-service interruption through recurring RPD restarts.

The record

CVE
CVE-2021-31377
Published
Oct 19, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-732, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 19, 2021CVE 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=15.1 <15.1R7-S9
  2. Affected versionversion=17.3 <17.3R3-S12
  3. Affected versionversion=17.4 <17.4R2-S13, 17.4R3-S5
  4. Affected versionversion=18.1 <18.1R3-S13
  5. Affected versionversion=18.2 <18.2R3-S8
  6. Affected versionversion=18.3 <18.3R3-S5
  7. Affected versionversion=18.4 <18.4R2-S8, 18.4R3-S7
  8. Affected versionversion=19.1 <19.1R2-S3, 19.1R3-S5
  9. Affected versionversion=19.2 <19.2R3-S2
  10. Affected versionversion=19.3 <19.3R2-S6, 19.3R3-S2
  11. Affected versionversion=19.4 <19.4R1-S4, 19.4R2-S4, 19.4R3-S2
  12. Affected versionversion=20.1 <20.1R2-S2, 20.1R3
  13. Affected versionversion=20.2 <20.2R2-S3, 20.2R3
  14. Affected versionversion=20.3 <20.3R3
  15. Affected versionversion=20.4 <20.4R1-S1, 20.4R2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OSversion=15.1 <15.1R7-S9; version=17.3 <17.3R3-S12; version=17.4 <17.4R2-S13, 17.4R3-S5; version=18.1 <18.1R3-S13; version=18.2 <18.2R3-S8; version=18.3 <18.3R3-S5; version=18.4 <18.4R2-S8, 18.4R3-S7; version=19.1 <19.1R2-S3, 19.1R3-S5; version=19.2 <19.2R3-S2; version=19.3 <19.3R2-S6, 19.3R3-S2; version=19.4 <19.4R1-S4, 19.4R2-S4, 19.4R3-S2; version=20.1 <20.1R2-S2, 20.1R3; version=20.2 <20.2R2-S3, 20.2R3; version=20.3 <20.3R3; version=20.4 <20.4R1-S1, 20.4R2

Published CVSS scores

5.5Juniper Networks, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

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.

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No observations available

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

Weakness, pattern, technique

CWE-732Incorrect Permission Assignment for Critical Resource
T1499.004Application 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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