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CVE-2020-1631

9.8, critical Known exploited

Juniper Junos OS Path Traversal Vulnerability

CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
5% higher than 91.8% of scored CVEs
Exploitation
Confirmed in the wild
Published
4 May 20206 years ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 25 Mar 2022. US federal agencies had to remediate by 15 Apr 2022, a deadline that has passed.

Required action. Apply updates per vendor instructions.

Description

A vulnerability in the HTTP/HTTPS service used by J-Web, Web Authentication, Dynamic-VPN (DVPN), Firewall Authentication Pass-Through with Web-Redirect, and Zero Touch Provisioning (ZTP) allows an unauthenticated attacker to perform local file inclusion (LFI) or path traversal. Using this vulnerability, an attacker may be able to inject commands into the httpd.log, read files with 'world' readable permission file or obtain J-Web session tokens. In the case of command injection, as the HTTP service runs as user 'nobody', the impact of this command injection is limited. (CVSS score 5.3, vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) In the case of reading files with 'world' readable permission, in Junos OS 19.3R1 and above, the unauthenticated attacker would be able to read the configuration file. (CVSS score 5.9, vector CVSS:3.1/ AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N) If J-Web is enabled, the attacker could gain the same level of access of anyone actively logged into J-Web. If an administrator is logged in, the attacker could gain administrator access to J-Web. (CVSS score 8.8, vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) This issue only affects Juniper Networks Junos OS devices with HTTP/HTTPS services enabled. Junos OS devices with HTTP/HTTPS services disabled are not affected. If HTTP/HTTPS services are enabled, the following command will show the httpd processes: user@device> show system processes | match http 5260 - S 0:00.13 /usr/sbin/httpd-gk -N 5797 - I 0:00.10 /usr/sbin/httpd --config /jail/var/etc/httpd.conf To summarize: If HTTP/HTTPS services are disabled, there is no impact from this vulnerability. If HTTP/HTTPS services are enabled and J-Web is not in use, this vulnerability has a CVSS score of 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N). If J-Web is enabled, this vulnerability has a CVSS score of 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). Juniper SIRT has received a single report of this vulnerability being exploited in the wild. Out of an abundance of caution, we are notifying customers so they can take appropriate actions. Indicators of Compromise: The /var/log/httpd.log may have indicators that commands have injected or files being accessed. The device administrator can look for these indicators by searching for the string patterns "=*;*&" or "*%3b*&" in /var/log/httpd.log, using the following command: user@device> show log httpd.log | match "=*;*&|=*%3b*&" If this command returns any output, it might be an indication of malicious attempts or simply scanning activities. Rotated logs should also be reviewed, using the following command: user@device> show log httpd.log.0.gz | match "=*;*&|=*%3b*&" user@device> show log httpd.log.1.gz | match "=*;*&|=*%3b*&" Note that a skilled attacker would likely remove these entries from the local log file, thus effectively eliminating any reliable signature that the device had been attacked. This issue affects Juniper Networks Junos OS 12.3 versions prior to 12.3R12-S16; 12.3X48 versions prior to 12.3X48-D101, 12.3X48-D105; 14.1X53 versions prior to 14.1X53-D54; 15.1 versions prior to 15.1R7-S7; 15.1X49 versions prior to 15.1X49-D211, 15.1X49-D220; 16.1 versions prior to 16.1R7-S8; 17.2 versions prior to 17.2R3-S4; 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R2-S11, 17.4R3-S2; 18.1 versions prior to 18.1R3-S10; 18.2 versions prior to 18.2R2-S7, 18.2R3-S4; 18.3 versions prior to 18.3R2-S4, 18.3R3-S2; 18.4 versions prior to 18.4R1-S7, 18.4R3-S2 ; 18.4 version 18.4R2 and later versions; 19.1 versions prior to 19.1R1-S5, 19.1R3-S1; 19.1 version 19.1R2 and later versions; 19.2 versions prior to 19.2R2; 19.3 versions prior to 19.3R2-S3, 19.3R3; 19.4 versions prior to 19.4R1-S2, 19.4R2; 20.1 versions prior to 20.1R1-S1, 20.1R2.

Details

Vendor
Juniper
Product
Junos OS
Weakness
CWE-22 (opens in a new tab)
Status
Analyzed
Updated
17 Jun 2026
Assigner
sirt@juniper.net

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

References 2

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Juniper CVEs

Every Juniper CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability KEV EPSS 2% 4.4, medium
  • CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function Vulnerability KEV EPSS 1% 5.3, medium
  • CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification Vulnerability KEV EPSS 90% 5.3, medium
  • CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification Vulnerability KEV EPSS 95% 9.8, critical
  • CVE-2023-36846 Juniper Junos OS SRX Series Missing Authentication for Critical Function Vulnerability KEV EPSS 93% 5.3, medium
  • CVE-2023-36847 Juniper Junos OS EX Series Missing Authentication for Critical Function Vulnerability KEV EPSS 83% 5.3, medium
  • CVE-2015-7755 Juniper ScreenOS Improper Authentication Vulnerability KEV EPSS 61% 9.8, critical

Beyond this page

Is CVE-2020-1631 in your network?

This page tells you how dangerous CVE-2020-1631 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2020-1631 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.