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

Status: published. Published: 2026-09-01. Updated: 2026-11-06.

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).

## Remediation

- workaround: To mitigate this vulnerability, do not connect to untrusted SFTP servers. (source: CNA: redhat)

## Affected products and versions

- GNOME / gvfs (gvfs): ≥ 1.10.0; < 1.60.2 (affected, semver). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (gvfs): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (gvfs): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (gvfs): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (gvfs): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (gvfs): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.21% as of 2026-11-05; percentile 11.59%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-908

## Exploit evidence

- exploit: https://gitlab.gnome.org/GNOME/gvfs/-/issues/861 (ADP: CISA-ADP)

## References

- https://access.redhat.com/security/cve/CVE-2026-84267 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2526466 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://gitlab.gnome.org/GNOME/gvfs/-/issues/861 (CNA: redhat)

- https://gitlab.gnome.org/GNOME/gvfs/-/issues/861 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-84267; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-84267; retrieved 2026-11-06; source updated Not reported

Revision: 5d38f4205b530413ae2ef6d1d25369c4556843e0b44e396c9c035af162615fd4

Canonical: https://y2.dev/cve/CVE-2026-84267

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