CVE-2026-48101: 7-zip Use of Uninitialized Resource

Vulnerability summary

CVE-2026-48101 is a medium (CVSS 6.5) Use of Uninitialized Resource vulnerability in 7-zip. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 32.7% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 05-06-2026
   PublishedVulnerability first disclosed.
2. 05-06-2026
   Last modifiedVulnerability information updated.

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.

• CWE-908Use of Uninitialized ResourceThe product uses or accesses a resource that has not been initialized.