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CVE-2021-0251

27
FAUCET Score

CVE-2021-0251 is a NULL Pointer Dereference vulnerability in the Captive Portal Content Delivery (CPCD) services daemon of Juniper Networks Junos OS on MX Series devices with specific MS-PIC, MS-SPC3, MS-MIC, or MS-MPC cards. An unauthenticated attacker can send malformed HTTP packets to the device, leading to a Denial of Service (DoS) by crashing the mspmand process and impacting other services. The vulnerability has a CVSS v3.1 score of 8.6 (High), indicating a network-based attack with low complexity and high impact on availability. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 18.1, < 18.1R3-S9CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 18.2, < 18.2R3-S3CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 18.3, < 18.3R3-S1CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 18.4, < 18.4R3CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 19.2, < 19.2R2CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.6HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.06%
Probability of exploitation in next 30 days
EPSS Percentile
61.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0106 is in the 38th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

junipervendor investigatingvia nvd_reference
View patch

References

kb.juniper.net / JSA11144
Vendor Advisory