Bug 2492709 (CVE-2026-53236)

Summary:	CVE-2026-53236 kernel: tcp: restrict SO_ATTACH_FILTER to priv users
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's handling of TCP sockets. An unprivileged application can exploit this vulnerability by attaching a Berkeley Packet Filter (BPF) using the SO_ATTACH_FILTER option. This allows the application to conduct a side-channel attack, leading to the leakage of sensitive TCP sequence and acknowledgment numbers. This information disclosure could potentially be used to aid further attacks.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-06-25 10:01:40 UTC

In the Linux kernel, the following vulnerability has been resolved:

tcp: restrict SO_ATTACH_FILTER to priv users

This patch restricts the use of SO_ATTACH_FILTER (cBPF) on TCP sockets
to users with CAP_NET_ADMIN capability.

This blocks potential side-channel attack where an unprivileged application
attaches a filter to leak TCP sequence/acknowledgment numbers.

Comment 1 Mauro Matteo Cascella 2026-06-26 10:39:13 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062510-CVE-2026-53236-45bc@gregkh/T