Red Hat Enterprise Linux Chunked Transfer Encoding Parser encoding error

Summaryinfo

A vulnerability has been found in Red Hat Enterprise Linux and classified as very critical. This impacts an unknown function of the component Chunked Transfer Encoding Parser. This manipulation causes encoding error. The identification of this vulnerability is CVE-2026-66338. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Red Hat Enterprise Linux (the affected version unknown). It has been declared as very critical. Affected by this vulnerability is an unknown part of the component Chunked Transfer Encoding Parser. The manipulation with an unknown input leads to a encoding error vulnerability. The CWE definition for the vulnerability is CWE-172. The product does not properly encode or decode the data, resulting in unexpected values. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests.

The advisory is shared at access.redhat.com. This vulnerability is known as CVE-2026-66338 since 07/25/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 07/25/2026).

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 vulnerability database at EUVD (EUVD-2026-48752). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Red Hat

Name

• Enterprise Linux

License

• commercial

Website

• Vendor: https://www.redhat.com/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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