CVE-2025-52948
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 · uneditedAn Improper Handling of Exceptional Conditions vulnerability in Berkeley Packet Filter (BPF) processing of Juniper Networks Junos OS allows an attacker, in rare cases, sending specific, unknown traffic patterns to cause the FPC and system to crash and restart. BPF provides a raw interface to data link layers in a protocol independent fashion. Internally within the Junos kernel, due to a rare timing issue (race condition), when a BPF instance is cloned, the newly created interface causes an internal structure leakage, leading to a system crash. The precise content and timing of the traffic patterns is indeterminate, but has been seen in a lab environment multiple times. This issue is more likely to occur when packet capturing is enabled. See required configuration below. This issue affects Junos OS: * all versions before 21.2R3-S9, * from 21.4 before 21.4R3-S10, * from 22.2 before 22.2R3-S6, * from 22.4 before 22.4R3-S7, * from 23.2 before 23.2R2-S3, * from 23.4 before 23.4R2-S3, * from 24.2 before 24.2R1-S1, 24.2R2.
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 kernel BPF processing causes internal structure leakage when a BPF instance is cloned, triggered by specific unknown traffic patterns. The vulnerability leads to FPC and system crashes, with increased likelihood when packet capturing is enabled.
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< 21.2= 21.2= 21.4= 22.2= 22.4= 23.2= 23.4= 24.2CVSS 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 'show version detail' on the device CLI to obtain the installed Junos OS version.Affected if The installed version matches any of these: < 21.2, = 21.2, = 21.4, = 22.2, = 22.4, = 23.2, = 23.4, = 24.2
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Determine if packet capture is enabledReview the device configuration for any active BPF or packet capture instances using 'show configuration | match capture' or 'show configuration | match filter' at the [edit firewall] hierarchy.Affected if BPF-based packet capture is actively configured and running on the device.
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Check for recent FPC or system crashesReview system logs and crash information using 'show system crash' and 'show log messages' for recent FPC restarts or kernel panics.Affected if FPC crashes or system crashes are logged and coincide with traffic activity that could trigger the BPF race condition.
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Verify BPF-related processesUse 'show system processes extensive' or check for active BPF subsystem activity if accessible via shell with 'ps aux | grep bpf'.Affected if Multiple BPF instances or cloned BPF sessions are observed running.
The device is affected if it runs a Junos version in the listed ranges AND has BPF packet capture enabled or has experienced unexplained FPC crashes under traffic load.
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 · scoped21.2
Apply the vendor-supplied Junos OS patches for the listed version ranges. As a temporary workaround, consider disabling packet capture (BPF) if operationally feasible until the patch can be deployed.
21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S7, 23.2R2-S3, 23.4R2-S3, 24.2R1-S1, or 24.2R2 (depending on your current version branch)
- 1. Identify the current Junos OS version on the device using 'show version'
- 2. Determine which version branch your current release belongs to (21.2, 21.4, 22.2, 22.4, 23.2, 23.4, or 24.2)
- 3. Plan an upgrade to the appropriate fixed release for your branch: For 21.2.x upgrade to 21.2R3-S9 or later; For 21.4.x upgrade to 21.4R3-S10 or later; For 22.2.x upgrade to 22.2R3-S6 or later; For 22.4.x upgrade to 22.4R3-S7 or later; For 23.2.x upgrade to 23.2R2-S3 or later; For 23.4.x upgrade to 23.4R2-S3 or later; For 24.2.x upgrade to 24.2R1-S1 or 24.2R2 or later
- 4. Before upgrading, backup the current configuration using 'request system configuration backup'
- 5. Perform the upgrade using 'request system software add <package>' following Juniper's standard upgrade procedure
- 6. After reboot, verify the new version is running with 'show version'
- 7. Verify system stability and FPC status with 'show chassis fpc'
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
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- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2025-52948 — 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-2025-52948 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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