CVE intelligence and bounded remediation

CVE-2021-0242 — Juniper Junos security vulnerability

Medium CVSS 6.5

A vulnerability due to the improper handling of direct memory access (DMA) buffers on EX4300 switches on Juniper Networks Junos OS allows an attacker sending specific unicast frames to trigger a Denial of Service (DoS) condition by exhausting DMA buffers, causing the FPC to crash and the device to restart. The DMA buffer leak is seen when receiving these specific, valid unicast frames on an interface without Layer 2 Protocol Tunneling (L2PT) or dot1x configured. Interfaces with either L2PT or dot1x configured are not vulnerable to this issue. When this issue occurs, DMA buffer usage keeps increasing and the following error log messages may be observed: Apr 14 14:29:34.360 /kernel: pid 64476 (pfex_junos), uid 0: exited on signal 11 (core dumped) Apr 14 14:29:33.790 init: pfe-manager (PID 64476) terminated by signal number 11. Core dumped! The DMA buffers on the FPC can be monitored by the executing vty command 'show heap': ID Base Total(b) Free(b) Used(b) % Name -- ---------- ----------- ----------- ----------- --- ----------- 0 4a46000 268435456 238230496 30204960 11 Kernel 1 18a46000 67108864 17618536 49490328 73 Bcm_sdk 2 23737000 117440512 18414552 99025960 84 DMA buf <<<<< kee…

Severity
Medium
CVSS
6.5 (3.1)
Published
2021-04-22
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-119, CWE-241, CWE-770

Affected products

  • juniper / junos / 17.3

Showing 1 representative product identities from 180 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Buffer bounds, memory safety, and memory corruption

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify affected native-code versions, build flags, architectures, parsers, codecs, drivers, and input paths in all shipped artifacts.
  • Determine whether untrusted data reaches the affected routine and the process privilege, sandbox, and network exposure.
  • Confirm statically linked, vendored, firmware, and platform-provided copies, not only package-manager records.

Remediate safely

  • Apply the maintained upstream correction or replace the affected component, then rebuild every dependent artifact from clean inputs.
  • Adopt bounds-checked interfaces, validated sizes and integer conversions, clear ownership, and memory-safe components where practical.
  • Enable supported compiler and runtime hardening and add sanitized tests and fuzz regression seeds derived from non-weaponized fixtures.

Authoritative sources

Complete CVE record and remediation plan

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