CVE intelligence and bounded remediation

CVE-2021-0227 — Juniper Junos security vulnerability

High CVSS 7.5

An improper restriction of operations within the bounds of a memory buffer vulnerability in Juniper Networks Junos OS J-Web on SRX Series devices allows an attacker to cause Denial of Service (DoS) by sending certain crafted HTTP packets. Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition. When this issue occurs, web-management, NTP daemon (ntpd) and Layer 2 Control Protocol process (L2CPD) daemons might crash. This issue affects Juniper Networks Junos OS on SRX Series: 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S11, 17.4R3-S2; 18.2 versions prior to 18.2R3-S5; 18.3 versions prior to 18.3R2-S4, 18.3R3-S3; 18.4 versions prior to 18.4R2-S5, 18.4R3-S4; 19.1 versions prior to 19.1R3-S2; 19.2 versions prior to 19.2R1-S5, 19.2R3; 19.3 versions prior to 19.3R3; 19.4 versions prior to 19.4R2-S1, 19.4R3; 20.1 versions prior to 20.1R1-S2, 20.1R2;

Severity
High
CVSS
7.5 (3.1)
Published
2021-04-22
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-119

Affected products

  • juniper / junos / 17.3

Showing 1 representative product identities from 128 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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