Red Hat Enterprise Linux/gvfs SFTP backend read_string uninitialized variable

Summaryinfo

A vulnerability identified as problematic has been detected in Red Hat Enterprise Linux and gvfs. This affects the function read_string of the component SFTP backend. This manipulation causes uninitialized variable. This vulnerability is registered as CVE-2026-84267. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in Red Hat Enterprise Linux and gvfs (affected version not known). It has been declared as problematic. Affected by this vulnerability is the function read_string of the component SFTP backend. The manipulation with an unknown input leads to a uninitialized variable vulnerability. The CWE definition for the vulnerability is CWE-457. The code uses a variable that has not been initialized, leading to unpredictable or unintended results. As an impact it is known to affect confidentiality. The summary by CVE is:

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).

It is possible to read the advisory at access.redhat.com. This vulnerability is known as CVE-2026-84267 since 09/01/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/01/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Operating System

Vendor

• Red Hat

Name

• Enterprise Linux
• gvfs

License

• commercial

Website

• Vendor: https://www.redhat.com/

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