CVE-2021-20515

Privileged code execution via stack buffer overflow

Published Apr 30, 2021 · Updated Sep 16, 2024

Stack-based buffer overflow in IBM Informix Dynamic Server 14.10 allows local privileged users to execute code or crash the server. Informix performs improper bounds checking during an undisclosed local operation, allowing attacker-controlled data to overrun a stack buffer; IBM has not identified the affected component or input. Exploitation requires a locally authenticated, privileged account and can run arbitrary code in the server context or interrupt service by crashing the server.

CVSS severity6.7
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in IBM Informix Dynamic Server 14.10 allows local privileged users to execute code or crash the server. Informix performs improper bounds checking during an undisclosed local operation, allowing attacker-controlled data to overrun a stack buffer; IBM has not identified the affected component or input. Exploitation requires a locally authenticated, privileged account and can run arbitrary code in the server context or interrupt service by crashing the server.

The record

CVE
CVE-2021-20515
Published
Apr 30, 2021
Updated
Sep 16, 2024
Vendor
IBM
Product
IBM Informix Dynamic Server
Classifications
CWE-787, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Apr 30, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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?

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  1. Affected versionversion=14.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

IBM · IBM Informix Dynamic Serverversion=14.1

Published CVSS scores

6.7IBM CorporationCVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
6.7NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/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.

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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)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

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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