Service hang via cyclic SMB2 record offsets
Published Apr 30, 2026 · Updated Apr 30, 2026
Infinite looping in the SMB2 dissector in Wireshark 4.4.0 through 4.4.14 and 4.6.0 through 4.6.4 allows attackers to hang analysis. The dissect_smb2_notify_data_out and dissect_smb2_file_full_ea_info functions add packet-supplied next_offset values without rejecting backward movement, allowing 32-bit wraparound to cycle between records indefinitely. A malformed packet injected onto a captured network or opened from a trace file keeps Wireshark or TShark at full CPU until the process is forcibly terminated; live exploitation requires the target to capture the traffic, while file exploitation requires user interaction.
Summary
What happened
Infinite looping in the SMB2 dissector in Wireshark 4.4.0 through 4.4.14 and 4.6.0 through 4.6.4 allows attackers to hang analysis. The dissect_smb2_notify_data_out and dissect_smb2_file_full_ea_info functions add packet-supplied next_offset values without rejecting backward movement, allowing 32-bit wraparound to cycle between records indefinitely. A malformed packet injected onto a captured network or opened from a trace file keeps Wireshark or TShark at full CPU until the process is forcibly terminated; live exploitation requires the target to capture the traffic, while file exploitation requires user interaction.
The record
- CVE
- CVE-2026-5407
- Published
- Apr 30, 2026
- Updated
- Apr 30, 2026
- Vendor
- Wireshark Foundation
- Product
- Wireshark
- Classifications
- CWE-835, T1499
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 30, 2026CVE publishedPublication date reported by the CVE source.
- Apr 30, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.4.0 <4.4.15
- Affected versionversion=4.6.0 <4.6.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- SMB2 infinite-loop capture and packet generatorsproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo