Summary
Bender is publishing this advisory to inform customers about two vulnerabilities in the Linux kernel used by the EDGE500IP. CISA has added both vulnerabilities (CVE-2025-39682 and CVE-2025-39964) to its Known Exploited Vulnerabilities catalog.
Bender has analyzed the vulnerabilities and determined that the electrical safety of the devices is not affected. Exploitation on the EDGE500IP requires code execution on the device, which is not available to users. Bender nevertheless considers the vulnerabilities to be of medium risk and has fixed them in COMTRAXX firmware 5.1.1.
Impact
An attacker who is already able to execute code locally on the device could use the vulnerabilities in the kernel TLS implementation (CVE-2025-39682) or the AF_ALG crypto socket interface (CVE-2025-39964) to compromise the confidentiality, integrity and availability of the device.
Affected Product(s)
| Model no. | Product name | Affected versions |
|---|---|---|
| B95061250 | EDGE500IP | COMTRAXX Firmware 5.0.0<5.1.1 |
| Linux kernel | 6.6.52 |
Vulnerabilities
Expand / Collapse allIn the Linux kernel, the following vulnerability has been resolved:
tls: fix handling of zero-length records on the rx_list
Each recvmsg() call must process either
- only contiguous DATA records (any number of them)
- one non-DATA record
If the next record has different type than what has already been
processed we break out of the main processing loop. If the record
has already been decrypted (which may be the case for TLS 1.3 where
we don't know type until decryption) we queue the pending record
to the rx_list. Next recvmsg() will pick it up from there.
Queuing the skb to rx_list after zero-copy decrypt is not possible,
since in that case we decrypted directly to the user space buffer,
and we don't have an skb to queue (darg.skb points to the ciphertext
skb for access to metadata like length).
Only data records are allowed zero-copy, and we break the processing
loop after each non-data record. So we should never zero-copy and
then find out that the record type has changed. The corner case
we missed is when the initial record comes from rx_list, and it's
zero length.
In the Linux kernel, the following vulnerability has been resolved:
crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg
Issuing two writes to the same af_alg socket is bogus as the
data will be interleaved in an unpredictable fashion. Furthermore,
concurrent writes may create inconsistencies in the internal
socket state.
Disallow this by adding a new ctx->write field that indiciates
exclusive ownership for writing.
Mitigation
Restrict network access to the device to trusted networks and users, and do not install firmware from untrusted sources.
Remediation
Install COMTRAXX firmware 5.1.1 or later (https://www.bender.de/service-support/downloadbereich).
Acknowledgments
Bender GmbH & Co. KG thanks the following parties for their efforts:
- CERT@VDE for coordination (see https://certvde.com )
Revision History
| Version | Date | Summary |
|---|---|---|
| 1.0.0 | 10.11.2026 11:00 | Initial revision. |