Vulnerability in 7-Zip

[ Description ]Official 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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund14 Oct 2026WID-SEC-2026-3960

  7-Zip: Vulnerability allows information disclosure Translated from German

  CVE-2026-104086

[ References ]References

• 7-zip.org
• sourceforge.net/p/sevenzip/discussion/45797/thread/db6922e1d0
• www.vulncheck.com/advisories/7-zip-squashfs-uninitialized-memory-disclosure-via-uid-gid…