CVE-2021-0251

Junos OS: MX Series with MS-PIC, MS-SPC3, MS-MIC or MS-MPC: The BRAS Subscriber Services service activation portal is vulnerable to a Denial of Service (DoS) via malformed HTTP packets

HIGH

8.6

CVSS Score

Published: April 22, 2021 at 07:37 PM UTC

Updated: June 17, 2026 at 03:29 AM UTC

17 products affected across 2 vendorsJunosMx960Mx480

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Severity

HIGH8.6

Exploit prediction

EPSS 1%

Description

A NULL Pointer Dereference vulnerability in the Captive Portal Content Delivery (CPCD) services daemon (cpcd) of Juniper Networks Junos OS on MX Series with MS-PIC, MS-SPC3, MS-MIC or MS-MPC allows an attacker to send malformed HTTP packets to the device thereby causing a Denial of Service (DoS), crashing the Multiservices PIC Management Daemon (mspmand) process thereby denying users the ability to login, while concurrently impacting other mspmand services and traffic through the device. Continued receipt and processing of these malformed packets will create a sustained Denial of Service (DoS) condition. While the Services PIC is restarting, all PIC services will be bypassed until the Services PIC completes its boot process. An attacker sending these malformed HTTP packets to the device who is not part of the Captive Portal experience is not able to exploit this issue. This issue is not applicable to MX RE-based CPCD platforms. This issue affects: Juniper Networks Junos OS on MX Series 17.3 version 17.3R1 and later versions prior to 17.4 versions 17.4R2-S9, 17.4R3-S2; 18.1 versions prior to 18.1R3-S9; 18.2 versions prior to 18.2R3-S3; 18.3 versions prior to 18.3R3-S1; 18.4 versions prior to 18.4R3; 19.1 versions prior to 19.1R2-S2, 19.1R3; 19.2 versions prior to 19.2R2; 19.3 versions prior to 19.3R3. This issue does not affect: Juniper Networks Junos OS versions prior to 17.3R1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

17.3R1 ≤ v < 17.3*17.4 ≤ v < 17.4R2-S9, 17.4R3-S218.1 ≤ v < 18.1R3-S918.2 ≤ v < 18.2R3-S318.3 ≤ v < 18.3R3-S118.4 ≤ v < 18.4R319.1 ≤ v < 19.1R2-S2, 19.1R319.2 ≤ v < 19.2R219.3 ≤ v < 19.3R317.3 r1 17.3 r1-s1 17.3 r1-s4 17.3 r2 17.3 r2-s1 17.3 r2-s2 17.3 r2-s3 17.3 r2-s4 17.3 r2-s5 17.3 r3 17.3 r3-s1 17.3 r3-s10 17.3 r3-s2 17.3 r3-s3 17.3 r3-s4 17.3 r3-s5 17.3 r3-s6 17.3 r3-s7 17.3 r3-s8 17.3 r3-s9 17.3R1 17.4 17.4 r1 17.4 r1-s1 17.4 r1-s2 17.4 r1-s3 17.4 r1-s4 17.4 r1-s5 17.4 r1-s6 17.4 r1-s7 17.4 r2 17.4 r2-s1 17.4 r2-s2 17.4 r2-s3 17.4 r2-s4 17.4 r2-s5 17.4 r2-s6 17.4 r2-s7 17.4 r2-s8 17.4 r3 17.4 r3-s1 18.1 18.1 r1 18.1 r2 18.1 r2-s1 18.1 r2-s2 18.1 r2-s4 18.1 r3 18.1 r3-s1 18.1 r3-s2 18.1 r3-s3 18.1 r3-s4 18.1 r3-s5 18.1 r3-s6 18.1 r3-s7 18.1 r3-s8 18.2 18.2 r1 18.2 r1-s2 18.2 r1-s3 18.2 r1-s4 18.2 r1-s5 18.2 r2 18.2 r2-s1 18.2 r2-s2 18.2 r2-s3 18.2 r2-s4 18.2 r2-s5 18.2 r2-s6 18.2 r2-s7 18.2 r3 18.2 r3-s1 18.2 r3-s2 18.3 18.3 r1 18.3 r1-s1 18.3 r1-s2 18.3 r1-s3 18.3 r1-s4 18.3 r1-s5 18.3 r1-s6 18.3 r2 18.3 r2-s1 18.3 r2-s2 18.3 r2-s3 18.3 r2-s4 18.3 r3 18.4 18.4 r1 18.4 r1-s1 18.4 r1-s2 18.4 r1-s3 18.4 r1-s4 18.4 r1-s5 18.4 r1-s6 18.4 r1-s7 18.4 r2 18.4 r2-s1 18.4 r2-s2 18.4 r2-s3 18.4 r2-s4 18.4 r2-s5 18.4 r2-s6 19.1 19.1 r1 19.1 r1-s1 19.1 r1-s2 19.1 r1-s3 19.1 r1-s4 19.1 r1-s5 19.1 r2 19.1 r2-s1 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4 19.2 r1-s5 19.3 19.3 r1 19.3 r1-s1 19.3 r2 19.3 r2-s1 19.3 r2-s2 19.3 r2-s3 19.3 r2-s4 19.3 r2-s5

Affected range stops below 17.3*, so it looks safe — our inference, not a vendor statement

Vendor states this is fixed in 17.3R1 (unaffected)

Affected range stops below 17.4R2-S9, 17.4R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.1R3-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.2R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3R3-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R2-S2, 19.1R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.3R3, so it looks safe — our inference, not a vendor statement

juniper-mx10 (environment) · juniper-mx10003 (environment) · juniper-mx10008 (environment) · juniper-mx10016 (environment) · juniper-mx104 (environment) · juniper-mx150 (environment) · juniper-mx2008 (environment) · juniper-mx2010 (environment) · juniper-mx2020 (environment) · juniper-mx204 (environment) · juniper-mx240 (environment) · juniper-mx40 (environment) · juniper-mx480 (environment) · juniper-mx5 (environment) · juniper-mx80 (environment) · juniper-mx960 (environment)

Mx10 · Juniperdevice

80%

All versions

Mx10003 · Juniperdevice

80%

All versions

Mx10008 · Juniperdevice

80%

All versions

Mx10016 · Juniperdevice

80%

All versions