CVE-2026-21906

Junos OS: SRX Series: With GRE performance acceleration enabled, receipt of a specific ICMP packet causes the PFE to crash

State: Published
Severity: 8.7 High
Published: Jan 15, 2026
Updated: Jan 16, 2026
Reserved: Jan 5, 2026

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Description

An Improper Handling of Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated network-based attacker sending a specific ICMP packet through a GRE tunnel to cause the PFE to crash and restart.

When PowerMode IPsec (PMI) and GRE performance acceleration are enabled and the device receives a specific ICMP packet, a crash occurs in the SRX PFE, resulting in traffic loss. PMI is enabled by default, and GRE performance acceleration can be enabled by running the configuration command shown below. PMI is a mode of operation that provides IPsec performance improvements using Vector Packet Processing.

Note that PMI with GRE performance acceleration is only supported on specific SRX platforms. This issue affects Junos OS on the SRX Series:

* all versions before 21.4R3-S12, * from 22.4 before 22.4R3-S8, * from 23.2 before 23.2R2-S5, * from 23.4 before 23.4R2-S5, * from 24.2 before 24.2R2-S3, * from 24.4 before 24.4R2-S1, * from 25.2 before 25.2R1-S1, 25.2R2.

Scores

CVSS	Score	Vector	Source
4.0	8.7 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Red	juniper
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	juniper

Weaknesses

CWE-755 Improper Handling of Exceptional Conditions

Affected Products

Product	Versions
Junos OSJuniper Networks	before 21.4R3-S12Affected 22.4 to before 22.4R3-S8Affected 23.2 to before 23.2R2-S5Affected 23.4 to before 23.4R2-S5Affected 24.2 to before 24.2R2-S3Affected 24.4 to before 24.4R2-S1Affected 25.2 to before 25.2R1-S1, 25.2R2Affected

References

https://supportportal.juniper.net/JSA106005vendor-advisory
https://www.juniper.net/documentation/us/en/software/junos/vpn-ipsec/topics/topic-map/security-powermode-ipsec-vpn.htmltechnical-description
https://kb.juniper.net/JSA106005vendor-advisory

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