CVE-2026-21906

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

HIGH

7.5

CVSS Score

Published: January 15, 2026 at 08:20 PM UTC

Updated: June 17, 2026 at 10:19 AM UTC

1 product affected across 1 vendorJunos

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Severity

HIGH7.5

Exploit prediction

EPSS 0.5%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

v < 21.4v < 21.4R3-S1222.4 ≤ v < 22.4R3-S823.2 ≤ v < 23.2R2-S523.4 ≤ v < 23.4R2-S524.2 ≤ v < 24.2R2-S324.4 ≤ v < 24.4R2-S125.2 ≤ v < 25.2R1-S1, 25.2R221.4 21.4 r1 21.4 r1-s1 21.4 r1-s2 21.4 r2 21.4 r2-s1 21.4 r2-s2 21.4 r3 21.4 r3-s1 21.4 r3-s10 21.4 r3-s11 21.4 r3-s2 21.4 r3-s3 21.4 r3-s4 21.4 r3-s5 21.4 r3-s6 21.4 r3-s7 21.4 r3-s8 21.4 r3-s9 22.4 22.4 r1 22.4 r1-s1 22.4 r1-s2 22.4 r2 22.4 r2-s1 22.4 r2-s2 22.4 r3 22.4 r3-s1 22.4 r3-s2 22.4 r3-s3 22.4 r3-s4 22.4 r3-s5 22.4 r3-s6 22.4 r3-s7 23.2 23.2 r1 23.2 r1-s1 23.2 r1-s2 23.2 r2 23.2 r2-s1 23.2 r2-s2 23.2 r2-s3 23.2 r2-s4 23.4 23.4 r1 23.4 r1-s1 23.4 r1-s2 23.4 r2 23.4 r2-s1 23.4 r2-s2 23.4 r2-s3 23.4 r2-s4 24.2 24.2 r1 24.2 r1-s1 24.2 r1-s2 24.2 r2 24.2 r2-s1 24.2 r2-s2 24.4 24.4 r1 24.4 r1-s2 24.4 r1-s3 24.4 r2 25.2 25.2 r1 25.2 r2

Affected range stops below 21.4R3-S12, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.4R3-S8, so it looks safe — our inference, not a vendor statement

Affected range stops below 23.2R2-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 23.4R2-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 24.2R2-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 24.4R2-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 25.2R1-S1, 25.2R2, so it looks safe — our inference, not a vendor statement

juniper-srx1500 (environment) · juniper-srx1600 (environment) · juniper-srx2300 (environment) · juniper-srx300 (environment) · juniper-srx320 (environment) · juniper-srx340 (environment) · juniper-srx345 (environment) · juniper-srx380 (environment) · juniper-srx4100 (environment) · juniper-srx4120 (environment) · juniper-srx4200 (environment) · juniper-srx4300 (environment) · juniper-srx4600 (environment) · juniper-srx4700 (environment) · juniper-srx5400 (environment) · juniper-srx5600 (environment) · juniper-srx5800 (environment)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

Vendor Advisory

Source: cverecord

https://supportportal.juniper.net/JSA106005

Technical Description

Source: cverecord

https://www.juniper.net/documentation/us/en/software/junos/vpn-ipsec/topics/topic-map/security-powermode-ipsec-vpn.html

Vendor Advisory

Source: cverecord

https://kb.juniper.net/JSA106005

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHjuniper

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-755

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