CVE-2020-12886Public exploitNetwork attack vector

Buffer over-read via unchecked CoAP token length

Published Jun 18, 2020 · Updated Aug 4, 2024

Out-of-bounds read in Arm Mbed OS 5.15.3 allows remote attackers to trigger reads past a CoAP packet buffer or crash the device. sn_coap_parser_options_parse() trusts the header's token-length field and passes that length to sn_coap_protocol_malloc_copy() without checking the remaining packet bytes. The affected device must parse a crafted CoAP packet; the resulting copy can incorporate adjacent memory into the parsed token or trigger an access violation.

CVSS severity9.1
Critical
EPSS probability1.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Arm Mbed OS 5.15.3 allows remote attackers to trigger reads past a CoAP packet buffer or crash the device. sn_coap_parser_options_parse() trusts the header's token-length field and passes that length to sn_coap_protocol_malloc_copy() without checking the remaining packet bytes. The affected device must parse a crafted CoAP packet; the resulting copy can incorporate adjacent memory into the parsed token or trigger an access violation.

The record

CVE
CVE-2020-12886
Published
Jun 18, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-125, T1499
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

7.8NISTAV:N/AC:L/Au:N/C:P/I:N/A:P
9.1NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

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-125Out-of-bounds Read
T1499Endpoint Denial of Service

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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