CVE-2021-22156Network attack vector

Code execution or crash via calloc overflow

Published Aug 17, 2021 · Updated Aug 22, 2025

Integer overflow in the C runtime library of BlackBerry QNX products allows remote attackers to execute code or crash affected devices. The calloc() implementation fails to detect overflow when multiplying attacker-controlled element counts and sizes, causing an undersized allocation before later memory access. Exploitation requires control of the calloc() parameters and subsequent memory access; network reachability enables remote attack when a vulnerable device is internet-exposed.

CVSS severity9.0
Critical
EPSS probability1.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in the C runtime library of BlackBerry QNX products allows remote attackers to execute code or crash affected devices. The calloc() implementation fails to detect overflow when multiplying attacker-controlled element counts and sizes, causing an undersized allocation before later memory access. Exploitation requires control of the calloc() parameters and subsequent memory access; network reachability enables remote attack when a vulnerable device is internet-exposed.

The record

CVE
CVE-2021-22156
Published
Aug 17, 2021
Updated
Aug 22, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-190, CAPEC-92
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 22, 2025Record 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

9.0BlackBerryCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
CAPEC-92Forced Integer Overflow

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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