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Fencer Intel
medium 5.8

CVE-2026-54576 json

mport package installation has symlink TOCTOU in chown and chmod handling

published 5mo ago modified last mo. also EUVD-2026-82329 , GHSA-23g3-7fv3-3ccf

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository MidnightBSD/mport. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
5.8
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

mport is the MidnightBSD Package Manager. Prior to 2.7.8, do_actual_install() in libmport/bundle_read_install_pkg.c used path-based lstat(), chown(), stat(), and chmod() operations while installing package files. A local attacker with write access to a target directory could replace a checked file with a symlink before privileged ownership or mode changes were applied, redirecting those changes to an attacker-selected path and compromising filesystem integrity or permissions. This issue is fixed in version 2.7.8.

Patch / fix

Is CVE-2026-54576 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 5.8 CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
CNA 4.0 5.8 CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • MidnightBSD mport

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of MidnightBSD/mport published their own advisory on GitHub. Reviewed sources take precedence over it.