CVE-2023-49558Public exploit

Assembler crash via invalid macro parameter read

Published Jan 2, 2024 · Updated Jun 3, 2025

A segmentation violation in Yasm 1.3.0.86.g9def allows context-dependent attackers to crash the assembler with a crafted input file. The expand_mmac_params function reads mac->paramlen[n] at nasm-pp.c:4013 while expanding macro parameters, and the crafted input drives that read to an invalid address. Exploitation requires Yasm to process the file and terminates only the affected assembler process.

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 segmentation violation in Yasm 1.3.0.86.g9def allows context-dependent attackers to crash the assembler with a crafted input file. The expand_mmac_params function reads mac->paramlen[n] at nasm-pp.c:4013 while expanding macro parameters, and the crafted input drives that read to an invalid address. Exploitation requires Yasm to process the file and terminates only the affected assembler process.

The record

CVE
CVE-2023-49558
Published
Jan 2, 2024
Updated
Jun 3, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 2, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 3, 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

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

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1204.002Malicious File

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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