NewsCompaniesFlawsGuides
Get the app

CVE-2020-1631

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Juniper Junos OS. For every flaw being used in attacks, see Exploited flaws; for Juniper’s, see Juniper flaws being used in attacks.

CVE-2020-1631 is a security flaw in Juniper Junos OS, the operating system on Juniper’s routers and firewalls. Attackers can run their own code on Juniper Junos OS from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 Mar 2022.[1]

Juniper Junos OS is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 12.3R12-S16, 12.3X48-D101, 12.3X48-D105, 14.1X53-D54 and 15.1R7-S7 and others of Junos OS.

Description

CISA calls it a path traversal in Juniper Junos OS. In its words: “A path traversal 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 remote code execution.”[1]

The CVE record adds: “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/…”[2]

The underlying weakness is path traversal (CWE-22), CWE-73, in MITRE’s list of common software weaknesses.

It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]

ProductFixed in
Junos OS12.3R12-S16
Junos OS12.3X48-D101, 12.3X48-D105
Junos OS14.1X53-D54
Junos OS15.1R7-S7
Junos OS15.1X49-D211, 15.1X49-D220
Junos OS16.1R7-S8
Junos OS17.2R3-S4
Junos OS17.3R3-S8

Most families won’t have Juniper Junos OS; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 25 Mar 2022, 690 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 15 Apr 2022 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 5%. That’s in the top 8% of the flaws it scores.[4]

CISA assesses it as not automatable: each attack takes some work.

CISA doesn’t say who was attacked, or how.

Fix

Juniper has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]

  1. Check whether you use it.Juniper Junos OS is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 12.3R12-S16, 12.3X48-D101, 12.3X48-D105, 14.1X53-D54 and 15.1R7-S7 and others of Junos OS), or not in use. CISA gave US government agencies until 15 Apr 2022 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 5%.[4]

See also

Other Juniper Junos OS flaws

  • CVE-2025-21590: improper isolation or compartmentalization ·
  • CVE-2023-36851: SRX series missing authentication for critical function ·
  • CVE-2023-36847: EX series missing authentication for critical function ·
  • CVE-2023-36846: SRX series missing authentication for critical function ·
  • CVE-2023-36845: EX series and SRX series PHP external variable modification ·
  • CVE-2023-36844: EX series PHP external variable modification ·

Other Juniper flaws

  • CVE-2015-7755, Juniper ScreenOS: improper authentication ·

Other path traversal flaws

  • CVE-2025-61624, Fortinet products: path traversal ·
  • CVE-2021-3199, ONLYOFFICE Docs: server path traversal ·
  • CVE-2026-104286, Fortinet FortiMail: path traversal ·
  • CVE-2026-93616, Check Point products: path traversal ·
  • CVE-2026-66384, JFrog Artifactory: improper limitation of a pathname to a restricted directory ·

Added the same day

  • CVE-2022-26318, WatchGuard Firebox and XTM Appliances: arbitrary code execution ·
  • CVE-2022-26143, Mitel MiCollab, MiVoice Business Express: access control ·
  • CVE-2022-21999, Microsoft Windows: print spooler privilege escalation ·
  • CVE-2021-42237, Sitecore XP: remote command execution ·
  • CVE-2021-22941, Citrix ShareFile: improper access control ·

Every Juniper flaw on CISA’s list · Everything added in March 2022

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “Juniper Junos OS Path Traversal Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 Mar 2022.
  2. ^ National Institute of Standards and Technology. “CVE-2020-1631 Detail”. National Vulnerability Database, published 4 May 2020.
  3. ^ Juniper. Advisories and fixes: kb.juniper.net.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.049, percentile 92.0, 31 Oct 2026.
  5. CVE Program. “CVE-2020-1631”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.