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Fencer Intel
high 7.3

CVE-2026-55601 json

MultiTail: Shell injection in execute-on-match command handling

published 4mo ago modified 26d ago also EUVD-2026-100521 , GHSA-54vm-wwx8-856h

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository folkertvanheusden/multitail. 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
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

MultiTail is a utility for monitoring multiple log files in one terminal. In version 7.1.5 and earlier, the -ex and -eX execute-on-match feature appended attacker-controlled matched input to a configured command inside double quotes, then check_filter_exec() in mt.c passed the constructed command through execute_program() in exec.c to sh -c. Partial escaping left shell metacharacters such as command substitution active, allowing an attacker who could influence monitored input to execute commands as the user running MultiTail. No fixed release is available as of this review.

Patch / fix

Is CVE-2026-55601 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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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-55601 updated cvss 7.3

multitail: multitail: Arbitrary command execution via improper input escaping in execute-on-match feature

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
29d ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/folkertvanheusden/multitail/security/advisories/GHSA-54vm-wwx8-856h referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

Affected products

  • folkertvanheusden multitail

Classification

Weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command

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 folkertvanheusden/multitail published their own advisory on GitHub. Reviewed sources take precedence over it.