Packet injection via mixed-protection fragment reassembly
Published May 11, 2021 · Updated Apr 14, 2026
Improper input validation in Siemens SCALANCE W firmware before 3.0.0 or 6.6.0 allows physically proximate attackers to inject or expose packets. Its Wi-Fi receive path reassembles frames containing both encrypted and plaintext fragments instead of rejecting the inconsistent protection state. Exploitation requires Wi-Fi range, another device sending fragmented frames, WEP, CCMP, or GCMP, and user interaction; impact is limited to packet injection or selected-fragment disclosure.
Summary
What happened
Improper input validation in Siemens SCALANCE W firmware before 3.0.0 or 6.6.0 allows physically proximate attackers to inject or expose packets. Its Wi-Fi receive path reassembles frames containing both encrypted and plaintext fragments instead of rejecting the inconsistent protection state. Exploitation requires Wi-Fi range, another device sending fragmented frames, WEP, CCMP, or GCMP, and user interaction; impact is limited to packet injection or selected-fragment disclosure.
The record
- CVE
- CVE-2020-26147
- Published
- May 11, 2021
- Updated
- Apr 14, 2026
- Vendor
- Siemens
- Product
- SCALANCE W786-2 RJ45
- Classifications
- CWE-20, T1557
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 11, 2021CVE publishedPublication date reported by the CVE source.
- Apr 14, 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.
Public exploit references
- FragAttacks testing toolfunctional · demonstrated
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Technologies
Your stack
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Your stack
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