Security readout for executives and security teams
Plain-English summary
A vulnerable Junos OS device running DHCPv6 local server or DHCPv6 relay can have its JDHCPD process crash when it receives a specific DHCPv6 packet. The daemon restarts automatically, but repeated packets can keep the service down, creating a sustained denial of service for DHCPv6-dependent operations.
Executive priority
Treat this as high priority for networks relying on Juniper DHCPv6 services, especially access or provider edge environments. The issue affects availability, not data theft, but repeated crashes could disrupt address assignment or relay functions until fixed or exposure is reduced.
Technical view
CVE-2021-0241 is a Junos OS JDHCPD availability flaw affecting DHCPv6 local server and DHCPv6 relay configurations across listed 17.3 through 20.3 trains. CVSS 3.1 is 7.4, adjacent network, low complexity, unauthenticated, no user interaction, changed scope, availability high. DHCPv4 is not affected.
Likely exposure
Exposure is limited to Juniper Junos OS systems on affected releases that are configured for DHCPv6 local server or DHCPv6 Relay Agent. Systems not using DHCPv6 for these roles are not described as affected in the provided sources.
Exploitation context
The bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector indicates an unauthenticated adjacent-network attack path, so practical exposure depends on who can send DHCPv6 traffic to the affected interface.
Researcher notes
This is CWE-703 improper exceptional condition handling in JDHCPD. Evidence supports DHCPv6-only impact and daemon restart behavior. The sources do not provide packet details, exploit code, or active exploitation claims, so validation should focus on configuration, version matching, and crash telemetry.
Mitigation direction
- Upgrade Junos OS to the fixed maintenance release for your installed train listed by Juniper.
- Review Juniper advisory JSA11168 for platform-specific upgrade guidance and operational notes.
- Remove unnecessary DHCPv6 local server or relay configurations after operational review.
- Limit DHCPv6 traffic reachability to trusted adjacent network segments where feasible.
Validation and detection
- Inventory Junos OS devices and record exact installed release trains.
- Identify devices configured as DHCPv6 local server or DHCPv6 Relay Agent.
- Compare installed versions against Juniper's affected and fixed release list.
- Check device logs for repeated JDHCPD crashes, restarts, or core dumps.
- Confirm DHCPv4-only systems are not misclassified as affected.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CWE-703: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-0241 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H2.84Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.4HighVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.juniper.net/JSA11168CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
CWE mapping pending import
This CVE carries a CWE mapping that will resolve to a full Glexia CWE intelligence page after the official CWE import is complete.