CVE-2021-31349

Name: CVE-2021-31349
Creator: NVD / NIST
Published: 2021-10-19T19:15:08.477+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 1.67%

Last modified Jun 17, 2026

CVE-2021-31349 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. The usage of an internal HTTP header created an authentication bypass vulnerability (CWE-287), allowing an attacker to view internal files, change settings, manipulate services and execute arbitrary code. This issue affects all Juniper Networks 128 Technology Session Smart Router versions prior to 4.5.11, and all versions of 5.0 up to and including 5.0.1.. EPSS estimates a 1.67% chance of exploitation in the next 30 days.

Description

The usage of an internal HTTP header created an authentication bypass vulnerability (CWE-287), allowing an attacker to view internal files, change settings, manipulate services and execute arbitrary code. This issue affects all Juniper Networks 128 Technology Session Smart Router versions prior to 4.5.11, and all versions of 5.0 up to and including 5.0.1.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

1.67%

73.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-287

Affected Software

Vendor	Product	Versions
Juniper	128 Technology Session Smart Router Firmware	< 4.5.11
Juniper	128 Technology Session Smart Router Firmware	>= 5.0.0, <= 5.0.1

References

https://kb.juniper.net/JSA11256Vendor Advisory
https://kb.juniper.net/JSA11256Vendor Advisory

Timeline

Published: Oct 19, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31349?

How severe is CVE-2021-31349?

CVE-2021-31349 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 1.67% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31349?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31349?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST