CVE-2021-28211

Heap corruption via truncated LZMA decoded size

Published Jun 11, 2021 · Updated Aug 3, 2024

Heap-based buffer overflow in TianoCore EDK II edk2-stable202008 allows local users with administrative privileges to corrupt memory. LzmaUefiDecompressGetInfo truncates a 64-bit LZMA DecodedSize above 4 GB into a 32-bit allocation size before decompression writes the full output. A privileged local path must supply a crafted compressed firmware section; the overwrite can crash firmware processing or corrupt adjacent heap data.

CVSS severity6.7
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in TianoCore EDK II edk2-stable202008 allows local users with administrative privileges to corrupt memory. LzmaUefiDecompressGetInfo truncates a 64-bit LZMA DecodedSize above 4 GB into a 32-bit allocation size before decompression writes the full output. A privileged local path must supply a crafted compressed firmware section; the overwrite can crash firmware processing or corrupt adjacent heap data.

The record

CVE
CVE-2021-28211
Published
Jun 11, 2021
Updated
Aug 3, 2024
Vendor
TianoCore
Product
EDK II
Classifications
CWE-787, CWE-122
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jun 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=edk2-stable202008

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

TianoCore · EDK IIversion=edk2-stable202008

Published CVSS scores

6.7NIST NVDCVSS:3.1/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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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
CWE-122Heap-based Buffer 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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