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TI-2026-17621 Aliases CVE-2026-21921GHSA-fm5x-5pxq-6229

Use after free in Juniper Junos OS

Priority LOW 31CWE-416Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-416 and the CVSS impact.

Summary

A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS). When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered. This issue affects:  Junos OS:  * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2; Junos OS Evolved: * all versions before 22.4R3-S8-EVO, * 23.2 versions before 23.2R2-S5-EVO, * 23.4 versions before 23.4R2-EVO.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00372 31st percentileScored 2026-11-07
Fix Fixed Junos OS (Juniper Networks): 22.4R3-S8, 23.2R2-S5, 23.4R2Junos OS Evolved (Juniper Networks): 22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-EVO

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
JuniperJunos OSbefore 22.4R3-S8; 23.2 to before 23.2R2-S5; 23.4 to before 23.4R222.4R3-S8, 23.2R2-S5, 23.4R2Patch availableCNA
JuniperJunos OS Evolvedbefore 22.4R3-S8-EVO; 23.2 to before 23.2R2-S5-EVO; 23.4 to before 23.4R2-EVO22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-EVOPatch availableCNA
  • Junos OS VendorJuniper Affected before 22.4R3-S8; 23.2 to before 23.2R2-S5; 23.4 to before 23.4R2 Fixed in 22.4R3-S8, 23.2R2-S5, 23.4R2 Patch available CNA
  • Junos OS Evolved VendorJuniper Affected before 22.4R3-S8-EVO; 23.2 to before 23.2R2-S5-EVO; 23.4 to before 23.4R2-EVO Fixed in 22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-EVO Patch available CNA

CPE configurations NVD · 58

CPEVersionsRoleVendor
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*before 22.4VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*22.4VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*22.4 r1VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*22.4 r1-s1VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*22.4 r1-s2VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:*22.4 r2VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:*22.4 r2-s1VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:*22.4 r2-s2VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:*22.4 r3VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:*22.4 r3-s1VulnerableJuniper
  • cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:* Versions before 22.4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:* Versions 22.4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:* Versions 22.4 r1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:* Versions 22.4 r1-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:* Versions 22.4 r1-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:* Versions 22.4 r2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:* Versions 22.4 r2-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:* Versions 22.4 r2-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:* Versions 22.4 r3 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:* Versions 22.4 r3-s1 Vulnerable ·Juniper
Show 48 more CPE
CPEVersionsRoleVendor
cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:*22.4 r3-s2VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r3-s3:*:*:*:*:*:*22.4 r3-s3VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r3-s4:*:*:*:*:*:*22.4 r3-s4VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r3-s5:*:*:*:*:*:*22.4 r3-s5VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r3-s6:*:*:*:*:*:*22.4 r3-s6VulnerableJuniper
cpe:2.3:o:juniper:junos:22.4:r3-s7:*:*:*:*:*:*22.4 r3-s7VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*23.2VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*23.2 r1VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*23.2 r1-s1VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*23.2 r1-s2VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*23.2 r2VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*23.2 r2-s1VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*23.2 r2-s2VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:*23.2 r2-s3VulnerableJuniper
cpe:2.3:o:juniper:junos:23.2:r2-s4:*:*:*:*:*:*23.2 r2-s4VulnerableJuniper
cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*23.4VulnerableJuniper
cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*23.4 r1VulnerableJuniper
cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*23.4 r1-s1VulnerableJuniper
cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*23.4 r1-s2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:*:*:*:*:*:*:*:*before 22.4VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:-:*:*:*:*:*:*22.4VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r1:*:*:*:*:*:*22.4 r1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s1:*:*:*:*:*:*22.4 r1-s1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s2:*:*:*:*:*:*22.4 r1-s2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r2:*:*:*:*:*:*22.4 r2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s1:*:*:*:*:*:*22.4 r2-s1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s2:*:*:*:*:*:*22.4 r2-s2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3:*:*:*:*:*:*22.4 r3VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s1:*:*:*:*:*:*22.4 r3-s1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s2:*:*:*:*:*:*22.4 r3-s2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s3:*:*:*:*:*:*22.4 r3-s3VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s4:*:*:*:*:*:*22.4 r3-s4VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s5:*:*:*:*:*:*22.4 r3-s5VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s6:*:*:*:*:*:*22.4 r3-s6VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s7:*:*:*:*:*:*22.4 r3-s7VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:-:*:*:*:*:*:*23.2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r1:*:*:*:*:*:*23.2 r1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s1:*:*:*:*:*:*23.2 r1-s1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s2:*:*:*:*:*:*23.2 r1-s2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r2:*:*:*:*:*:*23.2 r2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s1:*:*:*:*:*:*23.2 r2-s1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s2:*:*:*:*:*:*23.2 r2-s2VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s3:*:*:*:*:*:*23.2 r2-s3VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s4:*:*:*:*:*:*23.2 r2-s4VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.4:-:*:*:*:*:*:*23.4VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.4:r1:*:*:*:*:*:*23.4 r1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s1:*:*:*:*:*:*23.4 r1-s1VulnerableJuniper
cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s2:*:*:*:*:*:*23.4 r1-s2VulnerableJuniper
  • cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:* Versions 22.4 r3-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r3-s3:*:*:*:*:*:* Versions 22.4 r3-s3 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r3-s4:*:*:*:*:*:* Versions 22.4 r3-s4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r3-s5:*:*:*:*:*:* Versions 22.4 r3-s5 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r3-s6:*:*:*:*:*:* Versions 22.4 r3-s6 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:22.4:r3-s7:*:*:*:*:*:* Versions 22.4 r3-s7 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:* Versions 23.2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:* Versions 23.2 r1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:* Versions 23.2 r1-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:* Versions 23.2 r1-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:* Versions 23.2 r2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:* Versions 23.2 r2-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:* Versions 23.2 r2-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:* Versions 23.2 r2-s3 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.2:r2-s4:*:*:*:*:*:* Versions 23.2 r2-s4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:* Versions 23.4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:* Versions 23.4 r1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:* Versions 23.4 r1-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:* Versions 23.4 r1-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:*:*:*:*:*:*:*:* Versions before 22.4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:-:*:*:*:*:*:* Versions 22.4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r1:*:*:*:*:*:* Versions 22.4 r1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s1:*:*:*:*:*:* Versions 22.4 r1-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s2:*:*:*:*:*:* Versions 22.4 r1-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r2:*:*:*:*:*:* Versions 22.4 r2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s1:*:*:*:*:*:* Versions 22.4 r2-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s2:*:*:*:*:*:* Versions 22.4 r2-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3:*:*:*:*:*:* Versions 22.4 r3 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s1:*:*:*:*:*:* Versions 22.4 r3-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s2:*:*:*:*:*:* Versions 22.4 r3-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s3:*:*:*:*:*:* Versions 22.4 r3-s3 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s4:*:*:*:*:*:* Versions 22.4 r3-s4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s5:*:*:*:*:*:* Versions 22.4 r3-s5 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s6:*:*:*:*:*:* Versions 22.4 r3-s6 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s7:*:*:*:*:*:* Versions 22.4 r3-s7 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:-:*:*:*:*:*:* Versions 23.2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r1:*:*:*:*:*:* Versions 23.2 r1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s1:*:*:*:*:*:* Versions 23.2 r1-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s2:*:*:*:*:*:* Versions 23.2 r1-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r2:*:*:*:*:*:* Versions 23.2 r2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s1:*:*:*:*:*:* Versions 23.2 r2-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s2:*:*:*:*:*:* Versions 23.2 r2-s2 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s3:*:*:*:*:*:* Versions 23.2 r2-s3 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s4:*:*:*:*:*:* Versions 23.2 r2-s4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.4:-:*:*:*:*:*:* Versions 23.4 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.4:r1:*:*:*:*:*:* Versions 23.4 r1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s1:*:*:*:*:*:* Versions 23.4 r1-s1 Vulnerable ·Juniper
  • cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s2:*:*:*:*:*:* Versions 23.4 r1-s2 Vulnerable ·Juniper

Remediation

  • Fix · CNA Junos OS (Juniper Networks) Fixed in 22.4R3-S8, 23.2R2-S5, 23.4R2
  • Fix · CNA Junos OS Evolved (Juniper Networks) Fixed in 22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-EVO

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-21921
  2. 2026-10-03 Alias added: GHSA-fm5x-5pxq-6229

References

Advisory 2

  • TI-2023-18638 Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to… KEVCVSS 3.1CRITICAL 9.8
  • TI-2020-01585 Out of Cycle Security Advisory: Junos OS: Security vulnerability in J-Web and web based (HTTP/HTTPS) services KEVCVSS 3.1CRITICAL 9.8
  • TI-2015-04610 Assertion failure in ISC BIND named via TKEY queries KEVCVSS 3.1HIGH 7.5
  • TI-2025-15550 Junos OS: An local attacker with shell access can execute arbitrary code KEVCVSS 4.0MEDIUM 6.7
  • TI-2023-18644 Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload and download arbitrary files KEVCVSS 3.1MEDIUM 5.3
  • TI-2023-18640 Junos OS: EX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary files KEVCVSS 3.1MEDIUM 5.3
See all 792 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences