CVE-2021-37786Public exploit

Physically triggered app crash via oversized dose number

Published Sep 27, 2021 · Updated Aug 4, 2024

Denial of service in FOITT COVID Certificate App and Check App for iOS 2.2.0 and earlier allows attackers to crash either app via a crafted QR code. The certificate-processing path fails to handle an oversized numeric dn dose-number field, even when the QR payload carries an invalid signature. A physically proximate attacker must present the code for scanning; each scan crashes the app and prevents certificate validation, without reported data disclosure or modification.

CVSS severity4.6
Medium
EPSS probability0.19%
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 FOITT COVID Certificate App and Check App for iOS 2.2.0 and earlier allows attackers to crash either app via a crafted QR code. The certificate-processing path fails to handle an oversized numeric dn dose-number field, even when the QR payload carries an invalid signature. A physically proximate attacker must present the code for scanning; each scan crashes the app and prevents certificate validation, without reported data disclosure or modification.

The record

CVE
CVE-2021-37786
Published
Sep 27, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-755
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 27, 2021CVE 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 vectorphysical
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.6NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

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)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions

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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