ICSA-22-104-04: Siemens SCALANCE FragAttacks

CISA's summary

Summary: Twelve vulnerabilities in the implementation of frame aggregation and fragmentation of the 802.11 standard, under the name of FragAttacks, have been published. Successful exploitation of these vulnerabilities could allow an attacker within Wi-Fi range to forge encrypted frames, which could result in sensitive data disclosure and possibly traffic manipulation. The advised Siemens products are only affected by some of the published vulnerabilities. Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where fixes are not, or not yet available.

Products, as the advisory lists them

DeSpy has not checked any unit, hardware revision or firmware.

Vulnerabilities in this advisory

• CVE-2020-24588 — CVE-2020-24588 · CWE-306

  The 802.11 standard that underpins Wi-Fi Protected Access (WPA, WPA2, and WPA3) and Wired Equivalent Privacy (WEP) doesn't require that the A-MSDU flag in the plaintext QoS header field is authenticated. Against devices that support receiving non-SSP A-MSDU frames (which is mandatory as part of 802.11n), an adversary can abuse this to inject arbitrary network packets.

• CVE-2020-26139 — CVE-2020-26139 · CWE-287

  An issue was discovered in the kernel in NetBSD 7.1. An Access Point (AP) forwards EAPOL frames to other clients even though the sender has not yet successfully authenticated to the AP. This might be abused in projected Wi-Fi networks to launch denial-of-service attacks against connected clients and makes it easier to exploit other vulnerabilities in connected clients.

• CVE-2020-26140 — CVE-2020-26140 · CWE-74

  An issue was discovered in the ALFA Windows 10 driver 6.1316.1209 for AWUS036H. The WEP, WPA, WPA2, and WPA3 implementations accept plaintext frames in a protected Wi-Fi network. An adversary can abuse this to inject arbitrary data frames independent of the network configuration.

• CVE-2020-26141 — CVE-2020-26141 · CWE-354

  An issue was discovered in the ALFA Windows 10 driver 6.1316.1209 for AWUS036H. The Wi-Fi implementation does not verify the Message Integrity Check (authenticity) of fragmented TKIP frames. An adversary can abuse this to inject and possibly decrypt packets in WPA or WPA2 networks that support the TKIP data-confidentiality protocol.

• CVE-2020-26143 — CVE-2020-26143 · CWE-20

  An issue was discovered in the ALFA Windows 10 driver 1030.36.604 for AWUS036ACH. The WEP, WPA, WPA2, and WPA3 implementations accept fragmented plaintext frames in a protected Wi-Fi network. An adversary can abuse this to inject arbitrary data frames independent of the network configuration.

• CVE-2020-26144 — CVE-2020-26144 · CWE-20

  An issue was discovered on Samsung Galaxy S3 i9305 4.4.4 devices. The WEP, WPA, WPA2, and WPA3 implementations accept plaintext A-MSDU frames as long as the first 8 bytes correspond to a valid RFC1042 (i.e., LLC/SNAP) header for EAPOL. An adversary can abuse this to inject arbitrary network packets independent of the network configuration.

• CVE-2020-26145 — CVE-2020-26145 · CWE-20

  An issue was discovered on Samsung Galaxy S3 i9305 4.4.4 devices. The WEP, WPA, WPA2, and WPA3 implementations accept second (or subsequent) broadcast fragments even when sent in plaintext and process them as full unfragmented frames. An adversary can abuse this to inject arbitrary network packets independent of the network configuration.

• CVE-2020-26146 — CVE-2020-26146 · CWE-20

  An issue was discovered on Samsung Galaxy S3 i9305 4.4.4 devices. The WPA, WPA2, and WPA3 implementations reassemble fragments with non-consecutive packet numbers. An adversary can abuse this to exfiltrate selected fragments. This vulnerability is exploitable when another device sends fragmented frames and the WEP, CCMP, or GCMP data-confidentiality protocol is used. Note that WEP is vulnerable to this attack by design.

• CVE-2020-26147 — CVE-2020-26147 · CWE-20

  An issue was discovered in the Linux kernel 5.8.9. The WEP, WPA, WPA2, and WPA3 implementations reassemble fragments even though some of them were sent in plaintext. This vulnerability can be abused to inject packets and/or exfiltrate selected fragments when another device sends fragmented frames and the WEP, CCMP, or GCMP data-confidentiality protocol is used.

Acknowledgments, as the advisory lists them

• Siemens ProductCERT: reported these vulnerabilities to CISA.

The advisory's legal notice

The use of Siemens Security Advisories is subject to the terms and conditions listed on: https://www.siemens.com/productcert/terms-of-use.

Sources

• The advisory at cisa.gov
• The CSAF document (JSON)

DeSpy's copy of this version is dated 2026-09-28.