CVE-2026-82358: Auth Bypass (CVSS 6.5)

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.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS — Exploit Prediction

0.0024

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-863 Incorrect Authorization

References

Other 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

Frequently Asked Questions

What is CVE-2026-82358? +

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. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-82358? +

CVE-2026-82358 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0024, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-82358? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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