CVE-2019-17211: An integer overflow was discovered in the CoAP library in Arm Mbed OS 5.14.0

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CRITICAL 9.8REMOTEMITIGATE

CVE-2019-17211 is a critical-severity flaw (CVSS 9.8) affecting mbed. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An integer overflow was discovered in the CoAP library in Arm Mbed OS 5.14.0. The function sn_coap_builder_calc_needed_packet_data_size_2() is used to calculate the required memory for the CoAP message from the sn_coap_hdr_s data structure. Both returned_byte_count and src_coap_msg_ptr->payload_len are of type uint16_t. When added together, the result returned_byte_count can wrap around the maximum uint16_t value. As a result, insufficient buffer

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.6% (top 15%)
CISA exploited list	No
Weakness	CWE-190
Published	2019-11-05
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: mbed

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-11-05 16:15 UTCPublished CVE record published
2026-06-17 02:23 UTCUpdated Record last modified

mbed mbed MITIGATE

Affected: 5.13.2 · 5.14.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.13.2

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2019-17211?

mbed: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-17211 being exploited?

CVE-2019-17211 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2019-17211 affect?

CVE-2019-17211 affects mbed. Severity is critical (CVSS 9.8). An integer overflow was discovered in the CoAP library in Arm Mbed OS 5.14.0. The function sn_coap_builder_calc_needed_packet_data_size_2() is used to calculate the required memory for the CoAP message from the sn_coap_hdr_s data structure.

How urgent is CVE-2019-17211?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

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References

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