# CVE-2026-84267: Gvfs: sftp: uninitialized heap disclosure in read_string()

> A malicious SFTP server can leak uninitialized heap memory from gvfsd-sftp, defeating ASLR and exposing sensitive process memory.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N`)
- **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:** 1 Sep 2026
- **Updated:** 2 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-84267, GHSA-7w8w-22g3-g4f8, UBUNTU-CVE-2026-84267

## What is CVE-2026-84267?

CVE-2026-84267 is a medium-severity vulnerability in GNOME Red Hat Enterprise Linux 10, published on 1 Sep 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

A flaw was found in the SFTP backend in gvfs. When mounting a share, a malicious SFTP server can cause read_string() to allocate a buffer with a certain length but the function does not verify that the buffer is completely filled, leaving the remainder of the buffer containing uninitialized heap contents. If the server sends a short FXP_HANDLE reply, these uninitialized bytes are taken as the file handle. The client will then echo these uninitialized bytes back to the server on all subsequent requests using that handle. With a length of 128 bytes, this issue allows the malicious server to deterministically read uninitialized heap memory from the gvfsd-sftp process, leaking its heap base and the load address of the libgio library, resulting in a deterministic defeat of Address Space Layout Randomization (ASLR).

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2026-84267?


## How do I fix CVE-2026-84267?

Apply the vendor's patch.

## Is CVE-2026-84267 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84267 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84267 and fix it if it is affected.

What it is: CVE-2026-84267 is a medium-severity vulnerability in GNOME Red Hat Enterprise Linux 10, published on 1 Sep 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-2026-84267 exists.

Affected product: GNOME Red Hat Enterprise Linux 10. 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-2026-84267/ (Markdown: https://insights.sbomify.com/CVE-2026-84267/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84267
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84267
- OSV: https://osv.dev/vulnerability/CVE-2026-84267

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84267/
Summaries are generated and may contain mistakes; the official description above is the record.