CVE-2021-20349

Local privilege gain via TIS_CODESET buffer overflow

Published Aug 9, 2021 · Updated Sep 16, 2024

Stack-based buffer overflow in IBM Workload Scheduler 9.4 and 9.5 allows local users to gain lower-level privileges. The Linux and Unix chkhltst program performs improper bounds checking when it processes the TIS_CODESET environment variable, allowing oversized input to overrun a stack buffer. The attack requires local execution with attacker-controlled environment data, and IBM does not specify the resulting privilege level or code-execution behavior.

CVSS severity5.9
Medium
EPSS probability0.25%
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 Workload Scheduler 9.4 and 9.5 allows local users to gain lower-level privileges. The Linux and Unix chkhltst program performs improper bounds checking when it processes the TIS_CODESET environment variable, allowing oversized input to overrun a stack buffer. The attack requires local execution with attacker-controlled environment data, and IBM does not specify the resulting privilege level or code-execution behavior.

The record

CVE
CVE-2021-20349
Published
Aug 9, 2021
Updated
Sep 16, 2024
Vendor
IBM
Product
IBM Workload Scheduler
Classifications
CWE-787, T1068
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 9, 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=9.4
  2. Affected versionversion=9.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

IBM · IBM Workload Schedulerversion=9.4; version=9.5

Published CVSS scores

4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
5.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
5.9IBM CorporationCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

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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