Fragment exfiltration via nonconsecutive packet reassembly
Published May 11, 2021 · Updated Jun 2, 2026
Improper input validation in Siemens SCALANCE W products allows physically proximate attackers to exfiltrate selected Wi-Fi fragments. Their WPA-family defragmentation logic reassembles encrypted fragments without requiring consecutive packet numbers, allowing fragments from intervening traffic to be combined. Exploitation requires Wi-Fi proximity, another device transmitting fragmented frames, and WEP, CCMP, or GCMP confidentiality; the bounded consequence is disclosure of selected fragments.
Summary
What happened
Improper input validation in Siemens SCALANCE W products allows physically proximate attackers to exfiltrate selected Wi-Fi fragments. Their WPA-family defragmentation logic reassembles encrypted fragments without requiring consecutive packet numbers, allowing fragments from intervening traffic to be combined. Exploitation requires Wi-Fi proximity, another device transmitting fragmented frames, and WEP, CCMP, or GCMP confidentiality; the bounded consequence is disclosure of selected fragments.
The record
- CVE
- CVE-2020-26146
- Published
- May 11, 2021
- Updated
- Jun 2, 2026
- Vendor
- Siemens
- Product
- SCALANCE W786-2 RJ45
- Classifications
- CWE-20
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 11, 2021CVE publishedPublication date reported by the CVE source.
- Jun 2, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <V6.6.0
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
- FragAttacks test toolfunctional · demonstrated
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Technologies
Your stack
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Your stack
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