Heap-memory disclosure via ignored capsule short read
Published Jun 5, 2026 · Updated Jun 5, 2026
Uninitialized-memory disclosure in 7-Zip 9.21 through 26.00 allows remote attackers to expose heap data via a crafted UEFI capsule. OpenCapsule allocates CapsuleImageSize bytes without zero-initialization, ignores a short-read result from ReadStream_FALSE, and GetStream writes the unread heap tail into extracted content. A user must extract the malicious .scap file; the disclosed bytes can include data left by earlier archive operations in the same process.
Summary
What happened
Uninitialized-memory disclosure in 7-Zip 9.21 through 26.00 allows remote attackers to expose heap data via a crafted UEFI capsule. OpenCapsule allocates CapsuleImageSize bytes without zero-initialization, ignores a short-read result from ReadStream_FALSE, and GetStream writes the unread heap tail into extracted content. A user must extract the malicious .scap file; the disclosed bytes can include data left by earlier archive operations in the same process.
The record
- CVE
- CVE-2026-48101
- Published
- Jun 5, 2026
- Updated
- Jun 5, 2026
- Vendor
- 7-Zip
- Product
- 7-Zip
- Classifications
- CWE-908, T1204.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 5, 2026CVE publishedPublication date reported by the CVE source.
- Jun 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 9.21, < 26.01
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- GHSL-2026-117 UEFI capsule PoC generatorproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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