CVE-2026-21909— Junos OS and Junos OS Evolved: Receipt of specific IS-IS update packet causes memory leak leading to RPD crash
Quick assessment
Affected
Juniper Networks Junos OS
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Juniper Networks Junos OS和Juniper Networks Junos OS Evolved都是美国瞻博网络（Juniper Networks）公司的产品。Juniper Networks Junos OS是一套专用于该公司的硬件设备的网络操作系统。该操作系统提供了安全编程接口和Junos SDK。Juniper Networks Junos OS Evolved是Junos OS 的升级版系统。 Juniper Networks Junos OS和Juniper Network
Possible ATT&CK Techniques 1 AI
T1499 · Endpoint Denial of Service
Get alerts for future matching vulnerabilities
Log in to subscribe
I. Basic Information for CVE-2026-21909
Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗
Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.
Vulnerability Title
Junos OS and Junos OS Evolved: Receipt of specific IS-IS update packet causes memory leak leading to RPD crash
Source: CVE Program / CVE List V5
Vulnerability Description
A Missing Release of Memory after Effective Lifetime vulnerability in the routing protocol daemon (rpd) Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated attacker controlling an adjacent IS-IS neighbor to send a specific update packet causing a memory leak. Continued receipt and processing of these packets will exhaust all available memory, crashing rpd and creating a Denial of Service (DoS) condition.
Memory usage can be monitored through the use of the 'show task memory detail' command. For example:
user@junos> show task memory detail | match ted-infra
TED-INFRA-COOKIE 25 1072 28 1184 229
user@junos>
show task memory detail | match ted-infra
TED-INFRA-COOKIE 31 1360 34 1472 307
This issue affects:
Junos OS:
* from 23.2 before 23.2R2,
* from 23.4 before 23.4R1-S2, 23.4R2,
* from 24.1 before 24.1R2;
Junos OS Evolved:
* from 23.2 before 23.2R2-EVO,
* from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO,
* from 24.1 before 24.1R2-EVO.
This issue does not affect Junos OS versions before 23.2R1 or Junos OS Evolved versions before 23.2R1-EVO.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
在移除最后引用时对内存的释放不恰当(内存泄露)
Source: CVE Program / CVE List V5
Vulnerability Title
Juniper Networks Junos OS和Juniper Networks Junos OS Evolved 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Juniper Networks Junos OS和Juniper Networks Junos OS Evolved都是美国瞻博网络（Juniper Networks）公司的产品。Juniper Networks Junos OS是一套专用于该公司的硬件设备的网络操作系统。该操作系统提供了安全编程接口和Junos SDK。Juniper Networks Junos OS Evolved是Junos OS 的升级版系统。 Juniper Networks Junos OS和Juniper Network
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Juniper Networks | Junos OS | 23.2 ~ 23.2R2 | - |
|
| Juniper Networks | Junos OS Evolved | 23.2 ~ 23.2R2-EVO | - |
|
II. Public POCs for CVE-2026-21909
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
Premium
No public POC found.
Login to generate AI POCIII. Intelligence Information for CVE-2026-21909
请登录查看更多情报信息。
Vendor Advisories for CVE-2026-21909 (1)
Same Patch Batch · Juniper Networks · 2026-01-15 · 23 CVEs total
| CVE-2026-21913 | 7.5 HIGH | Junos OS: EX4000: A high volume of traffic destined to the device leads to a crash and res |
| CVE-2026-21920 | 7.5 HIGH | Junos OS: SRX Series: If a specific request is processed by the DNS subsystem flowd will c |
| CVE-2025-60003 | 7.5 HIGH | Junos OS and Junos OS Evolved: BGP update with a set of specific attributes causes rpd cra |
| CVE-2026-21918 | 7.5 HIGH | Junos OS: SRX and MX Series: When TCP packets occur in a specific sequence flowd crashes |
| CVE-2026-21917 | 7.5 HIGH | Junos OS: SRX Series: Specifically malformed SSL packet causes FPC crash |
| CVE-2026-21914 | 7.5 HIGH | Junos OS: SRX Series: A specifically malformed GTP message will cause an FPC crash |
| CVE-2026-21905 | 7.5 HIGH | Junos OS: SRX Series, MX Series with MX-SPC3 or MS-MPC: Receipt of multiple specific SIP m |
| CVE-2026-21906 | 7.5 HIGH | Junos OS: SRX Series: With GRE performance acceleration enabled, receipt of a specific ICM |
| CVE-2025-59960 | 7.4 HIGH | Junos OS and Junos OS Evolved: DHCP Option 82 messages from clients being passed unmodifie |
| CVE-2026-21908 | 7.1 HIGH | Junos OS and Junos OS Evolved: Use after free vulnerability In 802.1X authentication daemo |
| CVE-2026-21903 | 6.5 MEDIUM | Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash |
| CVE-2026-21911 | 6.5 MEDIUM | Junos OS Evolved: Flapping management interface causes MAC learning on label-switched inte |
| CVE-2026-21910 | 6.5 MEDIUM | Junos OS: EX4k Series, QFX5k Series: In an EVPN-VXLAN configuration link flaps cause Inter |
| CVE-2026-0203 | 6.5 MEDIUM | Junos OS: Receipt of a specifically malformed ICMP packet causes an FPC restart |
| CVE-2026-21921 | 6.5 MEDIUM | Junos OS and Junos OS Evolved: When telemetry collectors are frequently subscribing and un |
| CVE-2025-52987 | 6.1 MEDIUM | Paragon Automation: A clickjacking vulnerability in the web server configuration has been |
| CVE-2026-21907 | 5.9 MEDIUM | Junos Space: TLS/SSL server supports use of static key ciphers (ssl-static-key-ciphers) |
| CVE-2025-60011 | 5.8 MEDIUM | Junos OS and Junos OS Evolved: Optional transitive BGP attribute is modified before propag |
| CVE-2026-21912 | 5.5 MEDIUM | Junos OS: MX10k Series: 'show system firmware' CLI command may lead to LC480 or LC2101 lin |
| CVE-2025-60007 | 5.5 MEDIUM | Junos OS: A specifically crafted 'show chassis' command causes chassisd to crash |
Showing top 20 of 23 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same product: Junos OS
-
CVE-2026-57054
Junos OS: MX Series: Web filtering doesn't block specificall -
CVE-2026-57032
Junos OS: EX Series: Subscribing to an unsupported telemetry -
CVE-2026-57031
Junos OS: MX Series: For subscribers configured on static in -
CVE-2026-57030
Junos OS: SRX Series: Flow sessions are not getting cleared -
CVE-2026-57027
Junos OS: EX4100 Series, EX4400: With sFlow configured in a
Same vendor: Juniper Networks
-
CVE-2026-57054
Junos OS: MX Series: Web filtering doesn't block specificall -
CVE-2026-57032
Junos OS: EX Series: Subscribing to an unsupported telemetry -
CVE-2026-57031
Junos OS: MX Series: For subscribers configured on static in -
CVE-2026-57030
Junos OS: SRX Series: Flow sessions are not getting cleared -
CVE-2026-57029
Junos OS Evolved: QFX Series: When sFlow collector reachabil
Same weakness: CWE-401
-
CVE-2026-59295
Micrometer Instrumentation of Apache HttpAsyncClient Denial -
CVE-2026-12999
Infineon Airoc Wi-Fi driver leaks TX buffers on send failure -
CVE-2026-76235
Cockpit-ws: cockpit: cockpit-ws: unauthenticated remote memo -
CVE-2026-52734
ZEBRA: Unbounded memory leak in mempool download pipeline vi -
CVE-2026-73565
@hono/node-server: Unauthenticated memory-leak DoS via abort
V. Comments for CVE-2026-21909
No comments yet