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CVE-2021-31374

Junos OS and Junos OS Evolved: RPD crash while processing a specially crafted BGP UPDATE or KEEPALIVE message.

High7.5EPSS 1.0%
Published
Updated
Reserved
Assigned by
juniper

Description

On Juniper Networks Junos OS and Junos OS Evolved devices processing a specially crafted BGP UPDATE or KEEPALIVE message can lead to a routing process daemon (RPD) crash and restart, causing a Denial of Service (DoS). Continued receipt and processing of this message will create a sustained Denial of Service (DoS) condition. This issue affects both IBGP and EBGP deployments over IPv4 or IPv6. This issue affects: Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3-S1; 19.4 versions prior to 19.4R1-S4, 19.4R1-S4, 19.4R2-S3, 19.4R3-S1; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2; 20.3 versions prior to 20.3R1-S1, 20.3R2. Juniper Networks Junos OS Evolved: 20.3 versions prior to 20.3R2-EVO.

Scores

CVSS scores of CVE-2021-31374, by who scored it
Scored byCVSSScoreVector
juniperCNA (assigner)3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Modified3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
1.0% · top 36% of all CVEs (7 Nov 2026)
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

Affected products

  • Juniper Networks · Junos OS

    • affected 17.3 – < 17.3R3-S11
    • affected 17.4 – < 17.4R2-S13, 17.4R3-S4
    • affected 18.1 – < 18.1R3-S12
    • affected 18.2 – < 18.2R2-S8, 18.2R3-S7
    • affected 18.3 – < 18.3R3-S4
    • affected 18.4 – < 18.4R1-S8, 18.4R2-S7, 18.4R3-S7
    • affected 19.1 – < 19.1R1-S6, 19.1R2-S2, 19.1R3-S4
    • affected 19.2 – < 19.2R1-S6, 19.2R3-S1
    • affected 19.3 – < 19.3R2-S5, 19.3R3-S1
    • affected 19.4 – < 19.4R1-S4, 19.4R2-S3, 19.4R3-S1
    • affected 20.1 – < 20.1R2
    • affected 20.2 – < 20.2R2
    • affected 20.3 – < 20.3R1-S1, 20.3R2

  • Juniper Networks · Junos OS Evolved

    • affected 20.3 – < 20.3R2-EVO

What to do

Solution: The following software releases have been updated to resolve this specific issue: Junos OS: 17.3R3-S11, 17.4R2-S13, 17.4R3-S4, 18.1R3-S12, 18.2R2-S8, 18.3R3-S4, 18.4R1-S8, 18.4R2-S7, 18.4R3-S7, 19.1R1-S6, 19.1R2-S2, 19.1R3-S4, 19.2R1-S6, 19.2R3-S1, 19.3R2-S5, 19.3R3-S1, 19.4R1-S4, 19.4R2-S3, 19.4R3-S1, 20.1R2, 20.1R3, 20.2R2, 20.2R3, 20.3R1-S1, 20.3R2, 20.4R1, and all subsequent releases. Junos OS Evolved: 20.3R2-EVO 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 (1)

Sources

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

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Record last updated .