CVE-2026-48103: 7-zip Out-of-bounds Read

Vulnerability summary

CVE-2026-48103 is a high (CVSS 7.1) Out-of-bounds Read vulnerability in 7-zip. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 25.8% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 05-06-2026
   PublishedVulnerability first disclosed.
2. 08-06-2026
   Last modifiedVulnerability information updated.

Description

7-Zip is a file archiver with a high compression ratio. Versions 9.34 through 26.00 contain an off-by-one heap out-of-bounds read in the WIM (Windows Imaging) archive handler's security descriptor lookup. In CHandler::GetSecurity (CPP/7zip/Archive/Wim/WimHandler.cpp), the per-image SecurOffsets table holds numEntries + 1 cumulative offsets, but the check securityId >= SecurOffsets.Size() admits securityId == numEntries, and the function then reads SecurOffsets[securityId + 1], fetching one UInt32 past the end of the heap-allocated CRecordVector (which performs no bounds checking on operator[]). The securityId is attacker-controlled at offset +0xC of any directory entry in WIM metadata, and the handler is registered for .wim, .swm, .esd, and .ppkg and enabled by default in stock 7z.dll; the OOB triggers zero-click in the GUI because 7zFM.exe's ListView calls GetRawProp(kpidNtSecure) for every item during listing (ASan-confirmed), and is also reachable via CLI listing with 7zz l -slt. Impact is limited to denial of service under hardened allocators and minor information disclosure, since the OOB value is only consumed arithmetically as a length and is not surfaced to the attacker; there is no write primitive.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.