CVE-2026-54580Network attack vector

Index corruption and service interruption via zstd failures

Published Sep 17, 2026 · Updated Sep 24, 2026

Improper zstd error handling in MidnightBSD Mport before 2.7.8 allows remote attackers to corrupt package indexes or interrupt service. The mport_decompress_zstd() path accepted incomplete streams or failed writes without always removing partial output, while index-fetch callers ignored some failures. Exploitation requires control of compressed index content served by a package mirror; the bounded result is index-integrity loss or package-management interruption.

CVSS severity8.3
High
EPSS probability0.26%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper zstd error handling in MidnightBSD Mport before 2.7.8 allows remote attackers to corrupt package indexes or interrupt service. The mport_decompress_zstd() path accepted incomplete streams or failed writes without always removing partial output, while index-fetch callers ignored some failures. Exploitation requires control of compressed index content served by a package mirror; the bounded result is index-integrity loss or package-management interruption.

The record

CVE
CVE-2026-54580
Published
Sep 17, 2026
Updated
Sep 24, 2026
Vendor
MidnightBSD
Product
Mport
Classifications
CWE-755, CWE-354
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 2026Record 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=< 2.7.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MidnightBSD · Mportversion=< 2.7.8

Published CVSS scores

8.3GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
CWE-354Improper Validation of Integrity Check Value

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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