CVE-2026-80427: bestzip before 2.2.6 and 3.0.x before 3.0.2 Argument Injection via Missing Option Delimiter

Severity: high (CVSS 8.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-26 · updated 2026-09-24
Weakness: CWE-88

Description

bestzip builds the argument list for the system zip utility without separating options from operands. The destination archive path and the caller-supplied source paths are passed to the child process with no -- delimiter between them, so any source entry beginning with a hyphen is interpreted by zip as an option rather than a file name. zip accepts -T to test the finished archive and -TT to name the command used to perform that test, so a source list containing those two entries and a command string causes zip to run that command through a shell once the archive has been written. An application that passes a file name or path it received from an untrusted source into the bestzip API therefore executes a command of the supplier's choosing. Versions 2.2.6 and 3.0.2 add the delimiter.

Affected products

nfriedly bestzip: before 2.2.6; from 3.0.0 before 3.0.2 — fixed in 2.2.6, 3.0.2

How to fix

Upgrade to a fixed version: nfriedly bestzip 2.2.6, 3.0.2. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-80427 or the next vulnerability affects your stack