CVE-2020-12883

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 1.8%, top 24% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 9.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Buffer over-reads were discovered in the CoAP library in Arm Mbed OS 5.15.3. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses CoAP input linearly using a while loop. Once an option is parsed in a loop, the current point (*packet_data_pptr) is increased correspondingly. The pointer is restricted by the size of the received buffer, as well as by the option delta and option length bytes. The actual input packet length is not verified against the number of bytes read when processing the option extended delta and the option extended length. Moreover, the calculation of the message_left variable, in the case of non-extended option deltas, is incorrect and indicates more data left for processing than provided in the function input. All of these lead to heap-based or stack-based memory location read access that is outside of the intended boundary of the buffer. Depending on the platform-specific memory management mechanisms, it can lead to processing of unintended inputs or system memory access violation errors.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
46(Track)
EG Risk 46/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
77%
KEV
Not listed

Published

June 18, 2020

Last Modified

November 21, 2024

Advisory Details (4)

Auto-updated Jul 20, 2026
Patch available. Sources: github_pr.
generic

Out of range memory access in MbedOS CoAP library parser - option value length · Issue #12927 · ARMmbed/mbed-os · GitHub

https://github.com/ARMmbed/mbed-os/issues/12927
generic

Out of range memory access in MbedOS CoAP library parser - option number · Issue #12926 · ARMmbed/mbed-os · GitHub

https://github.com/ARMmbed/mbed-os/issues/12926
generic

Out of range memory access in MbedOS CoAP library parser · Issue #12925 · ARMmbed/mbed-os · GitHub

https://github.com/ARMmbed/mbed-os/issues/12925
github_pr Patch Available

Bugfix/coap parser mem access bugs

Patch available: ARMmbed/mbed-coap v5.1.8 (PR #116 merged 2020-06-22)

https://github.com/ARMmbed/mbed-coap/pull/116

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 30× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 123 total refreshes for this CVE.

  1. 2026-08-20 22:51 UTCEPSS rescore
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  1. 2026-07-23 14:15 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2020-12883?
CVE-2020-12883 is a critical vulnerability published on June 18, 2020. Buffer over-reads were discovered in the CoAP library in Arm Mbed OS 5.15.3. The CoAP parser is responsible for parsing received CoAP packets. The function sncoapparseroptionsparse() parses CoAP input linearly using a while loop. Once an option is parsed in a loop, the current point…
When was CVE-2020-12883 disclosed?
CVE-2020-12883 was first published in the National Vulnerability Database on June 18, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-12883 actively exploited?
CVE-2020-12883 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 23.5% of all scored CVEs.
What is the CVSS score of CVE-2020-12883?
CVE-2020-12883 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2020-12883?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-12883, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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