Junos OS: An attacker sending spoofed RADIUS messages to a Junos OS device configured for broadband services may cause broadband subscribers to remain stuck in a "Terminating" state.

Description

In broadband environments, including but not limited to Enhanced Subscriber Management, (CHAP, PPP, DHCP, etc.), on Juniper Networks Junos OS devices where RADIUS servers are configured for managing subscriber access and a subscriber is logged in and then requests to logout, the subscriber may be forced into a "Terminating" state by an attacker who is able to send spoofed messages appearing to originate from trusted RADIUS server(s) destined to the device in response to the subscriber's request. These spoofed messages cause the Junos OS General Authentication Service (authd) daemon to force the broadband subscriber into this "Terminating" state which the subscriber will not recover from thereby causing a Denial of Service (DoS) to the endpoint device. Once in the "Terminating" state, the endpoint subscriber will no longer be able to access the network. Restarting the authd daemon on the Junos OS device will temporarily clear the subscribers out of the "Terminating" state. As long as the attacker continues to send these spoofed packets and subscribers request to be logged out, the subscribers will be returned to the "Terminating" state thereby creating a persistent Denial of Service to the subscriber. An indicator of compromise may be seen by displaying the output of "show subscribers summary". The presence of subscribers in the "Terminating" state may indicate the issue is occurring. This issue affects: Juniper Networks Junos OS 17.3 versions prior to 17.3R3-S12; 17.4 versions prior to 17.4R3-S5; 18.1 versions prior to 18.1R3-S13; 18.2 versions prior to 18.2R3-S8; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R2-S8, 18.4R3-S9; 19.1 versions prior to 19.1R3-S6; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R1-S4, 19.4R1-S4, 19.4R3-S3; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3-S1; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2. This issue does not affect: Juniper Networks Junos OS 12.3 version 12.3R1 and later versions; 15.1 version 15.1R1 and later versions.

Timeline

Scores

EPSS (exploitation in 30 days)

1.0% · top 37% of all CVEs (7 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.8.

Weakness

• CWE-772: Missing Release of Resource after Effective Lifetime (opens in a new tab)All about CWE-772 and its CVEs
• Denial of Service (DoS)

Affected products

• Juniper Networks · Junos OS

  • affected 17.3 – < 17.3R3-S12
  • affected 17.4 – < 17.4R3-S5
  • affected 18.1 – < 18.1R3-S13
  • affected 18.2 – < 18.2R3-S8
  • affected 18.3 – < 18.3R3-S5
  • affected 18.4 – < 18.4R2-S8, 18.4R3-S9
  • affected 19.1 – < 19.1R3-S6
  • affected 19.2 – < 19.2R1-S7, 19.2R3-S3
  • affected 19.3 – < 19.3R2-S6, 19.3R3-S3
  • affected 19.4 – < 19.4R1-S4, 19.4R1-S4, 19.4R3-S3
  • affected 20.1 – < 20.1R3
  • affected 20.2 – < 20.2R3-S1
  • affected 20.3 – < 20.3R3
  • affected 20.4 – < 20.4R3
  • affected 21.1 – < 21.1R2
  • unaffected 12.3R1 – < 12.3*
  • unaffected 15.1R1 – < 15.1*

What to do

Solution: The following software releases have been updated to resolve this specific issue: 17.3R3-S12, 17.4R3-S5, 18.1R3-S13, 18.2R3-S8, 18.3R3-S5, 18.4R2-S8, 18.4R3-S9, 19.1R3-S6, 19.2R1-S7, 19.2R3-S3, 19.3R2-S6, 19.3R3-S3, 19.4R1-S4, 19.4R3-S3, 20.1R3, 20.2R3-S1, 20.3R3, 20.4R3, 21.1R2, 21.2R1, and all subsequent releases.

Workaround: There are no viable workarounds for this issue.

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

References (2)

• https://kb.juniper.net/JSA11246 (opens in a new tab)x_refsource_CONFIRMx_transferred
• https://www.juniper.net/documentation/us/en/software/junos/subscriber-mgmt-sessions/topics/topic-map/general-authentication-service-events-tracing.html (opens in a new tab)x_refsource_MISCx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2021-31378](https://trackcve.app/badge/CVE-2021-31378.svg)](https://trackcve.app/cve/CVE-2021-31378)

Record last updated 16 Sept 2024, 20:36 UTC.