CVE-2020-12885Public exploitNetwork attack vector

Unauthenticated service hang via zero-length CoAP option

Published Jun 18, 2020 · Updated Aug 4, 2024

Denial of service in the CoAP library in Arm Mbed OS 5.15.3 allows remote attackers to hang packet parsing with a crafted CoAP packet. The sn_coap_parser_options_parse_multiple_options() path treats a zero-byte heap requirement as a completed parse without advancing the packet pointer, so the outer options loop repeatedly processes the same option. Network reachability to a device using the affected parser is sufficient; the infinite loop consumes CPU time and can overload the system.

CVSS severity7.5
High
EPSS probability1.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the CoAP library in Arm Mbed OS 5.15.3 allows remote attackers to hang packet parsing with a crafted CoAP packet. The sn_coap_parser_options_parse_multiple_options() path treats a zero-byte heap requirement as a completed parse without advancing the packet pointer, so the outer options loop repeatedly processes the same option. Network reachability to a device using the affected parser is sufficient; the infinite loop consumes CPU time and can overload the system.

The record

CVE
CVE-2020-12885
Published
Jun 18, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 18, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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