CVE-2021-31349Network attack vector

Unauthenticated code execution via trusted internal header

Published Oct 19, 2021 · Updated Sep 16, 2024

Authentication bypass in Juniper Networks Session Smart Router before 4.5.11 and 5.0 through 5.0.1 allows remote attackers to execute arbitrary code. The HTTP authentication path trusts an internal-use header supplied by the client and treats the request as authenticated. No credentials or user interaction are required; access extends to internal files, settings, and service control, including arbitrary code execution.

CVSS severity9.8
Critical
EPSS probability1.72%
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 Juniper Networks Session Smart Router before 4.5.11 and 5.0 through 5.0.1 allows remote attackers to execute arbitrary code. The HTTP authentication path trusts an internal-use header supplied by the client and treats the request as authenticated. No credentials or user interaction are required; access extends to internal files, settings, and service control, including arbitrary code execution.

The record

CVE
CVE-2021-31349
Published
Oct 19, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Session Smart Router
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

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

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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=5.0 <=5.0.1
  2. Affected versionversion=unspecified <4.5.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Session Smart Routerversion=5.0 <=5.0.1; version=unspecified <4.5.11

Published CVSS scores

9.8Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/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.

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-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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