Hash: SHA256

             AUSCERT External Security Bulletin Redistribution

   JSA11159 - 2021-04 Security Bulletin: Junos OS: J-Web has an Improper
   Neutralization of CRLF Sequences in its HTTP Headers which allows an
     attacker to carry out multiple types of attacks. (CVE-2021-0268)
                                27 May 2021


        AusCERT Security Bulletin Summary

Product:           Junos OS
Publisher:         Juniper Networks
Operating System:  Juniper
Impact/Access:     Modify Arbitrary Files   -- Remote with User Interaction
                   Cross-site Scripting     -- Remote with User Interaction
                   Access Confidential Data -- Remote with User Interaction
                   Reduced Security         -- Remote with User Interaction
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-0268  

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

2021-04 Security Bulletin: Junos OS: J-Web has an Improper Neutralization of 
CRLF Sequences in its HTTP Headers which allows an attacker to carry out multiple
types of attacks. (CVE-2021-0268)

Article ID  : JSA11159
Last Updated: 26 May 2021
Version     : 2.0

Product Affected:
This issue affects Junos OS 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4,


An Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response
Splitting') weakness in J-web of Juniper Networks Junos OS leads to buffer
overflows, segment faults, or other impacts, which allows an attacker to modify
the integrity of the device and exfiltration information from the device
without authentication. 

The weakness can be exploited to facilitate cross-site scripting (XSS), cookie
manipulation (modifying session cookies, stealing cookies) and more. This 
weakness can also be exploited by directing a user to a seemingly legitimate link
from the affected site. 

The attacker requires no special access or permissions to the device to carry out
such attacks.

This issue affects:

Juniper Networks Junos OS:

  o 18.1 versions prior to 18.1R3-S11;
  o 18.2 versions prior to 18.2R3-S5;
  o 18.3 versions prior to 18.3R2-S4, 18.3R3-S3;
  o 18.4 versions prior to 18.4R2-S5, 18.4R3-S3;
  o 19.1 versions prior to 19.1R2-S2, 19.1R3-S2;
  o 19.2 versions prior to 19.2R1-S5, 19.2R2;
  o 19.3 versions prior to 19.3R3;
  o 19.4 versions prior to 19.4R1-S3, 19.4R2, 19.4R3;
  o 20.1 versions prior to 20.1R1-S2, 20.1R2.

  o This issue does not affect Juniper Networks Junos OS versions prior to

The following minimal configuration is necessary:

[system services web-management http]


[system services web-management https]

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned CVE-2021-0268 .


The following software releases have been updated to resolve this specific
issue: 18.1R3-S11, 18.2R3-S5, 18.3R2-S4, 18.3R3-S3, 18.4R2-S5, 18.4R3-S3,
19.1R2-S2, 19.1R3-S2, 19.2R1-S5, 19.2R2, 19.3R3, 19.4R1-S3, 19.4R2, 19.4R3,
20.1R1-S2, 20.1R2, 20.2R1, and all subsequent releases.

This issue is being tracked as 1503569 .


There are no viable workarounds for this issue other than disabling the J-Web

To reduce the risk of exploitation utilize common security BCPs to limit the
exploitable surface by limiting access to network and device to trusted
systems, administrators, networks and hosts.

Software releases or updates are available for download at https://
Modification History:

2021-04-14: Initial Publication.

CVSS Score: 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:L)

Severity Level: High

Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common
Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

The Juniper SIRT wishes to thank Luca Ercoli for responsibly reporting one of
the issues resolved in this update.

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:


Australian Computer Emergency Response Team
The University of Queensland
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
Comment: http://www.auscert.org.au/render.html?it=1967