CVE-2020-37280 PelionIoT CVE debrief

Who should care

Defenders responsible for systems using cbor-sync, especially those handling CBOR data, should assess exposure and prioritize verification and updates. This includes operators, platform administrators, vulnerability management teams, and security teams who need to verify cbor-sync versions in use, monitor for unusual patterns, and restrict input data to prevent exploitation.

Why it matters

This vulnerability allows remote attackers to cause memory exhaustion via crafted CBOR payloads. Defenders should verify and update cbor-sync, monitor for unusual patterns, and restrict input data to prevent exploitation.

• Potential for CPU exhaustion due to excessive iterations.
• Potential for process memory exhaustion.
• Need for verification of cbor-sync versions in use.
• Priority for updating or patching vulnerable instances.

Technical summary

The cbor-sync library through version 1.0.4 contains a resource exhaustion vulnerability. The CBOR.decode function does not check the remaining input when decoding, trusting declared array and map lengths. This allows remote attackers to provide tiny crafted CBOR payloads with huge lengths, leading to billions of iterations that exhaust CPU and process memory. The vulnerability is triggered by the lack of input validation on array and map lengths, which can be exploited by supplying crafted CBOR payloads with large declared lengths.

Defensive priority

Defenders should prioritize verifying and updating cbor-sync to a version beyond 1.0.4, especially in systems handling CBOR data.

Recommended defensive actions

• Verify cbor-sync version is beyond 1.0.4 in systems handling CBOR data.
• Implement monitoring for unusual CPU and memory usage patterns that could indicate exploitation attempts.
• Review and restrict input data to prevent supply of crafted CBOR payloads.
• Conduct an inventory of systems and applications using cbor-sync to identify potential exposure.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Evidence notes

The CVE record and source item provide details on the vulnerability but do not specify versions beyond 1.0.4 that are not affected or provide additional technical details on exploitation. Evidence is limited, and defenders should verify cbor-sync versions in use, review system logs for unusual activity, and restrict input data to prevent supply of crafted CBOR payloads. Further verification tasks are needed to confirm affected scope and severity.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.