CVE-2020-4839Network attack vector

Privileged service interruption via stack buffer overflow

Published May 25, 2021 · Updated Sep 16, 2024

Stack-based buffer overflow in IBM Power System S822LC host firmware OP820 allows remote authenticated users to crash the system. An undisclosed host-firmware code path copies network-supplied data into a stack buffer without adequate bounds checking. High-privilege access is required, and successful exploitation interrupts availability without reported data disclosure or modification.

CVSS severity4.9
Medium
EPSS probability1.52%
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 Power System S822LC host firmware OP820 allows remote authenticated users to crash the system. An undisclosed host-firmware code path copies network-supplied data into a stack buffer without adequate bounds checking. High-privilege access is required, and successful exploitation interrupts availability without reported data disclosure or modification.

The record

CVE
CVE-2020-4839
Published
May 25, 2021
Updated
Sep 16, 2024
Vendor
IBM
Product
IBM Power System S822LC (8335-GTB)
Classifications
CWE-787, T1499
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. May 25, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=OP820

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

IBM · IBM Power System S822LC (8335-GTB)version=OP820
IBM · IBM Power System S822LC (8335-GCA)version=OP820
IBM · IBM Power System S822LC (8335-GTA)version=OP820

Published CVSS scores

4.9IBMCVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
4.3IBMCVSS:3.0/PR:H/UI:N/AC:L/S:U/A:H/AV:N/I:N/C:N/RC:C/RL:O/E:U

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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