CVE-2026-104086
7-Zip < 26.03 SquashFS Uninitialized Memory Disclosure via UID/GID Table
7-Zip 7-ZipLibraries & packages
CVSS
6.8MediumExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.19%Chance of exploitation activity in the next 30 days, higher than 7% of CVEs. Scored 23 Oct 2026FIRST EPSS
What fixes it
- 26.037-ZipCVE List
A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.
Description
7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.
Text from CVE List
Affected versions 1
- 7-Zipaffected: all versions before 26.03CVE List