# CVE-2026-48103: GHSL-2026-119 7-Zip WIM SecurityId OOB read

> An off-by-one heap out-of-bounds read in 7-Zip's WIM handler allows attackers to cause denial of service or minor information disclosure via crafted archives.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L`)
- **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:** Yes
- **Published:** 5 Jun 2026
- **Updated:** 8 Jun 2026
- **Also known as:** ALPINE-CVE-2026-48103, DEBIAN-CVE-2026-48103, ECHO-3114-e2a8-c7cd, MINI-j8rf-6xmw-wphf, UBUNTU-CVE-2026-48103

## What is CVE-2026-48103?

CVE-2026-48103 is a medium-severity memory corruption 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 9.34 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.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-48103?

It affects 1 product.


Products: 7-Zip 7-Zip.

## How do I fix CVE-2026-48103?

Upgrade to a fixed version.

## Is CVE-2026-48103 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48103 exists.

## Other vulnerabilities in mcmilk 7-Zip

- [CVE-2025-0411](https://insights.sbomify.com/CVE-2025-0411/): 7-Zip Mark of the Web Bypass (high 7.0, exploited in the wild)
- [CVE-2008-6536](https://insights.sbomify.com/CVE-2008-6536/): Other in n/a (critical 10.0)
- [CVE-2026-48095](https://insights.sbomify.com/CVE-2026-48095/): GHSL-2026-140_7-Zip: 7-Zip has a heap buffer overflow via NTFS compressed stream buffer under-allocation (high 8.8)
- [CVE-2018-10172](https://insights.sbomify.com/CVE-2018-10172/): Privilege escalation in n/a (high 8.8)
- [CVE-2016-2335](https://insights.sbomify.com/CVE-2016-2335/): Memory corruption in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48103 and fix it if it is affected.

What it is: CVE-2026-48103 is a medium-severity memory corruption 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48103 exists.

Affected product: mcmilk 7-Zip. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-48103/ (Markdown: https://insights.sbomify.com/CVE-2026-48103/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48103
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48103
- OSV: https://osv.dev/vulnerability/CVE-2026-48103

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48103/
Summaries are generated and may contain mistakes; the official description above is the record.