CVE-2026-57030
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA 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;
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA race condition in Junos OS SRX Series packet forwarding engine causes flow timeout to be incorrectly set to >10,000 seconds instead of 3 seconds during flow removal, leading to flow accumulation, session invalidation, and eventual DoS via flowd crash or forwarding failure requiring manual reboot.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 24.2= 24.4= 25.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Junos OS versionRun 'show version' or 'request system version' command on the deviceAffected if Version shown is 24.2, 24.4, or 25.2 (or any sub-version of these releases)
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Confirm device is SRX SeriesCheck the hardware model using 'show chassis hardware' or 'show system information'Affected if Device model is in the SRX Series family (SRX340, SRX345, SRX550M, SRX1500, etc.)
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Check for abnormal flow timeout valuesUse 'show flow session summary' and 'show flow statistics' to inspect timeout settings; look for sessions with timeout values exceeding normal limitsAffected if Flow sessions show timeout values in the range of 10,000+ seconds instead of typical 3-second timeouts for expiring flows
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Monitor for flow accumulationReview 'show flow session' output and track session count growth over time; check 'show flow statistics' for unusual flow pool usageAffected if Session count continues to grow abnormally or flow pool approaches exhaustion without normal cleanup
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Check for flowd instabilityReview system logs (/var/log/messages) for flowd crash events, core dumps, or forwarding failures using 'show log messages | match flowd'Affected if Logs show flowd crashes, core dump files, or repeated forwarding failures indicating the DoS condition
A user is affected if running Junos OS 24.2, 24.4, or 25.2 on an SRX Series device and observing abnormally high flow timeouts or flow accumulation symptoms.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedApply vendor-provided patches: upgrade to 24.2R2-S3, 24.4R2-S1/S2, or 25.2R1-S2/25.2R2 or later per the Juniper advisory.
24.2R2-S3, 24.4R2-S2, or 25.2R2 (or later versions in respective branches)
- 1. Identify the current Junos OS version on the SRX Series device using 'show version'
- 2. Based on the current version branch, plan upgrade to the minimum fixed version: For 24.2 branch: upgrade to 24.2R2-S3 or later; For 24.4 branch: upgrade to 24.4R2-S2 or later; For 25.2 branch: upgrade to 25.2R2 or later
- 3. Before upgrading, back up the current configuration using 'request system configuration rescue save'
- 4. Download the appropriate Junos upgrade image from Juniper Networks support portal
- 5. Upgrade the device using 'request system software add <package>' and then 'request system reboot'
- 6. After reboot, verify the new version is running with 'show version'
- 7. Monitor flow sessions with 'show security flow session summary' to confirm invalidated sessions are not accumulating
- 8. Optionally verify flow timeouts are correctly set to ~3 seconds using 'show security flow session'
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-57030 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-57030 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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