CVE-2026-48101 GHSL-2026-117: 7-Zip UEFI Capsule uninitialized heap memory disclosure

Medium 6.5 Published 5 Jun 2026 Updated 5 Jun 2026

An attacker can disclose uninitialized heap memory by crafting a truncated UEFI capsule file, potentially exposing sensitive data from the victim's system.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-48101?

CVE-2026-48101 is a medium-severity vulnerability in mcmilk 7-Zip, published on 5 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

7-Zip is a file archiver with a high compression ratio. Versions 9.21 through 26.00 contain an An uninitialized memory disclosure vulnerability in the UEFI capsule (.scap) parser in 7-Zip. The OpenCapsule function allocates a heap buffer of attacker-declared CapsuleImageSize (up to 1 GiB) without zero-initialization, then reads the file contents into it with ReadStream_FALSE whose return value is silently discarded. If the file is truncated, the unread tail of the buffer retains uninitialized heap memory, which is then exposed as extracted file content via GetStream. Version 26.0.1 fixes the issue.

Weakness: CWE-908

Which versions are affected by CVE-2026-48101?

It affects 1 product.

Products include 7-Zip 7-Zip.

How do I fix CVE-2026-48101?

Upgrade to a fixed version.

Is CVE-2026-48101 being exploited?

There is no known exploitation of CVE-2026-48101 in the wild and no public exploit code.

Sources

Also known as ALPINE-CVE-2026-48101, DEBIAN-CVE-2026-48101, ECHO-7b47-8f62-c1ef, MINI-p9wf-x8pp-whqr, UBUNTU-CVE-2026-48101.