Vulnerability Details CVE-2026-57030
A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).
As part of the stateful traffic processing on SRX Series devices flows are being established, and removed when not needed anymore. During the removal process the timeout of a flow should be set to 3 seconds and consequentially the flow should be removed shortly after. Due to a race condition occurring when setting the timeout there is a chance (the exact conditions are outside the attackers control) that the timeout is instead set to a very high value of larger than 10,000 seconds:
user@host> show security flow session | match timeout
Session ID: 98784248524, Policy name: PROD-FLOW/4, HA State: Active, Timeout: 85250, Session State: Valid
This will lead to an accumulation of flows which can be observed by an ever-increasing value of invalidated sessions in the output of 'show security flow session summary':
user@host> show security flow session summary | match invalid
Invalidated sessions: 216931These sessions can't be cleared manually with the 'clear security flow session' command, which will either lead to forwarding to stop (and the system needs to be manually recovered with a reboot) or to a flowd core and automatic reboot.
This issue affects Junos OS on SRX Series:
* 24.2 versions before 24.2R2-S3,
* 24.4 versions before 24.4R2-S1, 24.4R2-S2,
* 25.2 versions before 25.2R1-S2, 25.2R2.
This issue does not affect releases earlier than 24.2R1;
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 30.2%
CVSS Severity
CVSS v3 Score 5.9
Products affected by CVE-2026-57030
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cpe:2.3:h:juniper:srx1500:-
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cpe:2.3:h:juniper:srx1600:-
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cpe:2.3:h:juniper:srx2300:-
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cpe:2.3:h:juniper:srx300:-
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cpe:2.3:h:juniper:srx320:-
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cpe:2.3:h:juniper:srx340:-
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cpe:2.3:h:juniper:srx345:-
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cpe:2.3:h:juniper:srx380:-
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cpe:2.3:h:juniper:srx400:-
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cpe:2.3:h:juniper:srx4100:-
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cpe:2.3:h:juniper:srx4200:-
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cpe:2.3:h:juniper:srx4300:-
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cpe:2.3:h:juniper:srx440:-
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cpe:2.3:h:juniper:srx4600:-
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cpe:2.3:h:juniper:srx5400:-
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cpe:2.3:h:juniper:srx5800:-
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cpe:2.3:o:juniper:junos:24.2
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cpe:2.3:o:juniper:junos:24.4
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cpe:2.3:o:juniper:junos:25.2