LiveActive security incident?Get immediate response
CVE Record

CVE-2021-0292: Junos OS Evolved: Memory leak in arpd or ndp processes can lead to Denial of Service (DoS)

An Uncontrolled Resource Consumption vulnerability in the ARP daemon (arpd) and Network Discovery Protocol (ndp) process of Juniper Networks Junos OS Evolved allows a malicious attacker on the local network to consume memory resources, ultimately resulting in a Denial of Service (DoS) condition. Link-layer functions such as IPv4 and/or IPv6 address resolution may be impacted, leading to traffic loss. The processes do not recover on their own and must be manually restarted. Changes in memory usage can be monitored using the following shell commands (header shown for clarity): user@router:/var/log# ps aux | grep arpd USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 31418 59.0 0.7 *5702564* 247952 ? xxx /usr/sbin/arpd --app-name arpd -I object_select --shared-objects-mode 3 user@router:/var/log# ps aux | grep arpd USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 31418 49.1 1.0 *5813156* 351184 ? xxx /usr/sbin/arpd --app-name arpd -I object_select --shared-objects-mode 3 Memory usage can be monitored for the ndp process in a similar fashion: user@router:/var/log# ps aux | grep ndp USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 14935 0.0 0.1 *5614052* 27256 ? Ssl Jun15 0:17 /usr/sbin/ndp -I no_tab_chk,object_select --app-name ndp --shared-obje user@router:/var/log# ps aux | grep ndp USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 14935 0.0 0.1 *5725164* 27256 ? Ssl Jun15 0:17 /usr/sbin/ndp -I no_tab_chk,object_select --app-name ndp --shared-obje This issue affects Juniper Networks Junos OS Evolved: 19.4 versions prior to 19.4R2-S3-EVO; 20.1 versions prior to 20.1R2-S4-EVO; all versions of 20.2-EVO. This issue does not affect Juniper Networks Junos OS Evolved versions prior to 19.4R2-EVO.

MediumCVSS 6.5Not KEV-listedUpdated
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

Affected Juniper Junos OS Evolved devices can be pushed into a memory leak in address-resolution services from the local network. If triggered, IPv4 or IPv6 neighbor resolution may fail, causing traffic loss. The impacted processes do not recover automatically and require manual restart.

Executive priority

Treat as a scheduled but important network reliability fix. It is not reported as actively exploited, but affected core or edge routing devices could suffer traffic loss and require manual process recovery if attacked from a local segment.

Technical view

CWE-400 uncontrolled resource consumption affects arpd and ndp. An adjacent unauthenticated attacker can consume memory, impacting ARP/NDP link-layer resolution. CVSS 3.1 is 6.5. Affected versions include 19.4 before 19.4R2-S3-EVO, 20.1 before 20.1R2-S4-EVO, and all listed 20.2-EVO versions.

Likely exposure

Exposure is limited to Juniper Networks Junos OS Evolved devices reachable from the same local network segment. Internet-wide exploitation is not indicated by the source bundle, but operational impact can be significant on affected routers handling production traffic.

Exploitation context

The CVE is not listed as CISA KEV in the provided bundle, and no cited source states active exploitation. The attack requires adjacent-network access, no privileges, no user interaction, and low complexity. Impact is availability-only, with traffic loss possible.

Researcher notes

Evidence is sufficient for affected version scoping, attack prerequisites, and availability impact. The bundle does not provide exploit details, workaround specifics, or a named fixed 20.2-EVO release. Do not infer broader Junos OS impact beyond Junos OS Evolved.

Mitigation direction

  • Review Juniper advisory JSA11194 for the approved fixed or recommended release.
  • Upgrade 19.4 systems to 19.4R2-S3-EVO or later where applicable.
  • Upgrade 20.1 systems to 20.1R2-S4-EVO or later where applicable.
  • For 20.2-EVO, follow current Juniper guidance; the bundle lists all 20.2-EVO as affected.
  • Restrict untrusted local-network access to affected routing infrastructure where operationally possible.

Validation and detection

  • Inventory Junos OS Evolved devices and compare versions against the affected ranges.
  • Confirm whether deployed devices run arpd, ndp, and affected EVO release trains.
  • Monitor arpd and ndp memory growth using vendor-recommended process checks.
  • Check for unexplained traffic loss linked to ARP or IPv6 neighbor discovery failures.
  • Verify remediation by confirming the installed release is outside the affected range.
Prepared
Confidence
high
Sources
3

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-400: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-0292 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

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.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
6.5CVSS 3.1MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H2.83.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

6.5Medium
CVSS 3.1 vector shape for CVE-2021-0292Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Juniper NetworksJunos OS Evolvedunspecified, 19.4, 20.1, 20.2R1-EVOListed
Weakness

CWE details

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-400 · source CWE mapping

Uncontrolled Resource Consumption

Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.