RT-Labs AB C-Open CANopen contains a write protection bypass in the SDO (Service Data Object)…

Why it is Yellow

• CVSS 6.5 medium

References

• https://github.com/rtlabs-com/c-open/releases/tag/public%2Fv1.1.1
• https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2025/va-26-275-02.json
• https://rt-labs.com/wp-content/uploads/2026/09/RRTL-260929-01.pdf
• https://www.cve.org/CVERecord?id=CVE-2026-82358

Original description

RT-Labs AB C-Open CANopen contains a write protection bypass in the SDO (Service Data Object) server implementation 'src/co_sdo_server.c' that fails to properly validate write permissions when processing download-segment frames. An unauthenticated attacker on the CAN bus can initiate an SDO upload for a read-only Object Dictionary (OD) entry, which sets a data pointer to the read-only object, then send download-segment frames to write to that memory location. The download-segment handler does not verify that a download session is active, allowing any CANopen node to overwrite read-only OD entries using two SDO frames. Note that CANopen protocol operates over CAN bus and does not provide built-in authentication mechanisms. Fixed in 1.1.1.