CVE-2025-21595

MEDIUM
Published Apr 9, 2025 Modified Jan 26, 2026 CWE-401

Description

A Missing Release of Memory after Effective Lifetime vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause an FPC to crash, leading to Denial of Service (DoS). On all Junos OS and Junos OS Evolved platforms, in an EVPN-VXLAN scenario, when specific ARP packets are received on an IPv4 network, or specific NDP packets are received on an IPv6 network, kernel heap memory leaks, which eventually leads to an FPC crash and restart. This issue does not affect MX Series platforms. Heap size growth on FPC can be seen using below command. user@host> show chassis fpc                     Temp CPU Utilization (%) CPU Utilization (%) Memory   Utilization (%) Slot State           (C) Total Interrupt     1min   5min   15min   DRAM (MB)   Heap   Buffer   0 Online           45     3         0       2       2      2       32768      19       0 <<<<<<< Heap increase in all fPCs This issue affects Junos OS: * All versions before 21.2R3-S7, * 21.4 versions before 21.4R3-S4, * 22.2 versions before 22.2R3-S1,  * 22.3 versions before 22.3R3-S1,  * 22.4 versions before 22.4R2-S2, 22.4R3. and Junos OS Evolved: * All versions before 21.2R3-S7-EVO, * 21.4-EVO versions before 21.4R3-S4-EVO, * 22.2-EVO versions before 22.2R3-S1-EVO,  * 22.3-EVO versions before 22.3R3-S1-EVO,  * 22.4-EVO versions before 22.4R3-EVO.

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CVSS v3.1 Score

6.5
MEDIUM
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-401 CWE-401

Affected Products

Vendor Product
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved
juniper junos_os_evolved

References

Frequently Asked Questions

What is CVE-2025-21595? +
A Missing Release of Memory after Effective Lifetime vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause an FPC to crash, leading to Denial of Service (DoS). On all Junos OS and Junos OS Evolved platforms, in an EVPN-VXLAN scenario, when specific ARP packets are received on an IPv4 network, or specific NDP packets are received on an IPv6 network, kernel heap memory leaks, which eventually leads to an FPC crash and restart. This issue does not affect MX Series platforms. Heap size growth on FPC can be seen using below command. user@host> show chassis fpc                     Temp CPU Utilization (%) CPU Utilization (%) Memory   Utilization (%) Slot State           (C) Total Interrupt     1min   5min   15min   DRAM (MB)   Heap   Buffer   0 Online           45     3         0       2       2      2       32768      19       0 <<<<<<< Heap increase in all fPCs This issue affects Junos OS: * All versions before 21.2R3-S7, * 21.4 versions before 21.4R3-S4, * 22.2 versions before 22.2R3-S1,  * 22.3 versions before 22.3R3-S1,  * 22.4 versions before 22.4R2-S2, 22.4R3. and Junos OS Evolved: * All versions before 21.2R3-S7-EVO, * 21.4-EVO versions before 21.4R3-S4-EVO, * 22.2-EVO versions before 22.2R3-S1-EVO,  * 22.3-EVO versions before 22.3R3-S1-EVO,  * 22.4-EVO versions before 22.4R3-EVO. It has a CVSS v3.1 base score of 6.5 (MEDIUM).
How severe is CVE-2025-21595? +
CVE-2025-21595 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2025-21595? +
CVE-2025-21595 affects products from juniper, specifically: junos, junos_os_evolved. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2025-21595? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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