7-Zip < 26.03 SquashFS Uninitialized Memory Disclosure via UID/GID Table

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.

Source published

14 Oct 2026 14:06:14 UTC

Source modified

19 Oct 2026 19:06:48 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 6.8 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS 3.1 · 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N