CVE-2026-57030: CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') in Juniper Networks Junos OS
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;
AI Analysis
Technical Summary
CVE-2026-57030 is a race condition vulnerability (CWE-362) in the packet forwarding engine of Juniper Networks Junos OS on SRX Series devices. During flow removal, a race condition may cause the timeout to be set to an excessively high value (>10,000 seconds) instead of the intended 3 seconds. This results in an accumulation of invalidated sessions that cannot be cleared manually, leading to denial-of-service conditions such as forwarding stoppage or flowd process crashes and automatic reboots. The vulnerability affects Junos OS versions 24.2 before 24.2R2-S3, 24.4 before 24.4R2-S1 and 24.4R2-S2, and 25.2 before 25.2R1-S2 and 25.2R2. Versions earlier than 24.2R1 are not affected. The CVSS 3.1 base score is 5.9 (medium severity), reflecting network attack vector with high attack complexity and no confidentiality or integrity impact but high availability impact. A patch is available, and since this is a cloud service, the vendor manages remediation server-side.
Potential Impact
An unauthenticated network attacker can exploit this race condition to cause a denial-of-service by causing the system to accumulate invalidated flow sessions that cannot be cleared manually. This can lead to forwarding stoppage or flowd process crashes resulting in automatic system reboots, impacting availability of affected Junos OS SRX Series devices.
Mitigation Recommendations
A patch is available for this vulnerability. Juniper Networks manages remediation for this cloud-hosted service; users should consult the vendor advisory for confirmation and apply the official fixes for affected Junos OS versions 24.2 before 24.2R2-S3, 24.4 before 24.4R2-S1 and 24.4R2-S2, and 25.2 before 25.2R1-S2 and 25.2R2. No additional manual mitigation is indicated.
CVE-2026-57030: CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') in Juniper Networks Junos OS
Description
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;
CVSS v3.1
Score 5.9medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-57030 is a race condition vulnerability (CWE-362) in the packet forwarding engine of Juniper Networks Junos OS on SRX Series devices. During flow removal, a race condition may cause the timeout to be set to an excessively high value (>10,000 seconds) instead of the intended 3 seconds. This results in an accumulation of invalidated sessions that cannot be cleared manually, leading to denial-of-service conditions such as forwarding stoppage or flowd process crashes and automatic reboots. The vulnerability affects Junos OS versions 24.2 before 24.2R2-S3, 24.4 before 24.4R2-S1 and 24.4R2-S2, and 25.2 before 25.2R1-S2 and 25.2R2. Versions earlier than 24.2R1 are not affected. The CVSS 3.1 base score is 5.9 (medium severity), reflecting network attack vector with high attack complexity and no confidentiality or integrity impact but high availability impact. A patch is available, and since this is a cloud service, the vendor manages remediation server-side.
Potential Impact
An unauthenticated network attacker can exploit this race condition to cause a denial-of-service by causing the system to accumulate invalidated flow sessions that cannot be cleared manually. This can lead to forwarding stoppage or flowd process crashes resulting in automatic system reboots, impacting availability of affected Junos OS SRX Series devices.
Mitigation Recommendations
A patch is available for this vulnerability. Juniper Networks manages remediation for this cloud-hosted service; users should consult the vendor advisory for confirmation and apply the official fixes for affected Junos OS versions 24.2 before 24.2R2-S3, 24.4 before 24.4R2-S1 and 24.4R2-S2, and 25.2 before 25.2R1-S2 and 25.2R2. No additional manual mitigation is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- juniper
- Date Reserved
- 2026-06-23T16:27:00.249Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Is Cloud Service
- true
Threat ID: 6a50171668715ace431ea20b
Added to database: 07/09/2026, 21:48:06 UTC
Last enriched: 07/17/2026, 09:50:32 UTC
Last updated: 08/22/2026, 22:52:14 UTC
Views: 78
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