CVE-2023-49555Public exploit

Assembler crash via null read in expand_smacro

Published Jan 2, 2024 · Updated Jun 17, 2025

A null-pointer dereference in YASM 1.3.0.86.g9def allows local users to crash the assembler via crafted assembly source. The expand_smacro function in modules/preprocs/nasm/nasm-pp.c reads through a null pointer while expanding malformed single-line macro input. Exploitation requires a user or build process to run YASM on the crafted file and interrupts only that assembler process; no confidentiality or integrity impact is reported.

CVSS severity5.5
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A null-pointer dereference in YASM 1.3.0.86.g9def allows local users to crash the assembler via crafted assembly source. The expand_smacro function in modules/preprocs/nasm/nasm-pp.c reads through a null pointer while expanding malformed single-line macro input. Exploitation requires a user or build process to run YASM on the crafted file and interrupts only that assembler process; no confidentiality or integrity impact is reported.

The record

CVE
CVE-2023-49555
Published
Jan 2, 2024
Updated
Jun 17, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 2, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 17, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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.

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 exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

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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