Red Hat Enterprise Linux up to 10 libsoup buffer overflow

Summaryinfo

A vulnerability was found in Red Hat Enterprise Linux 6/7/8/9/10. It has been declared as critical. Affected by this issue is some unknown functionality of the component libsoup. Executing a manipulation can lead to buffer overflow. This vulnerability is registered as CVE-2026-85534. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability has been found in Red Hat Enterprise Linux 6/7/8/9/10 and classified as critical. This vulnerability affects some unknown processing of the component libsoup. The manipulation with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. As an impact it is known to affect availability. CVE summarizes:

A flaw was found in libsoup. When a client sends an HTTP/2 request body from a non-pollable input stream, the library can buffer more data than the current flow-control window later allows. A malicious HTTP/2 server can shrink SETTINGS_INITIAL_WINDOW_SIZE while that buffered read is still in progress. The client then copies the full buffer into a smaller DATA callback without a runtime bounds check, which can abort the process or fail the HTTP/2 session.

The advisory is shared for download at access.redhat.com. This vulnerability was named CVE-2026-85534 since 09/04/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/05/2026).

The vulnerability scanner Nessus provides a plugin with the ID 342820 (Linux Distros Unpatched Vulnerability : CVE-2026-85534), which helps to determine the existence of the flaw in a target environment.

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

The vulnerability is also documented in the databases at Tenable (342820) and EUVD (EUVD-2026-70997). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Red Hat

Name

• Enterprise Linux

Version

• 6
• 7
• 8
• 9
• 10

License

• commercial

Website

• Vendor: https://www.redhat.com/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

Discussion