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CVE-2023-40548

Shim: interger overflow leads to heap buffer overflow in verify_sbat_section on 32-bits systems

High7.4EPSS 0.44%
Published
Updated
Reserved
Assigned by
redhat

Description

A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a user-controlled value parsed from the PE binary being used by Shim. This value is further used for memory allocation operations, leading to a heap-based buffer overflow. This flaw causes memory corruption and can lead to a crash or data integrity issues during the boot phase.

Timeline

  1. ID reserved

    By redhat

  2. · 6 months later

    Published

  3. · 2 years later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2023-40548, by who scored it
Scored byCVSSScoreVector
redhatCNA (assigner)3.1High7.4CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVDNVD · Modified3.1High7.4CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (exploitation in 30 days)
0.44% · top 62% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: total
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.4.

Weakness

Affected products

What to do

Workaround: There's no available mitigation for this issue.

References (12)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .