Bug 2528736 (CVE-2026-80875)

Summary:	CVE-2026-80875 kernel: ipvs: use parsed transport offset in TCP state lookup
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:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
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Doc Text:	A flaw was found in the IP Virtual Server (IPVS) component of the Linux kernel. When processing IPv6 packets with extension headers, the TCP state handling incorrectly parses the TCP header by using a fixed size for the IPv6 header instead of the actual transport-header offset. This can cause the system to misinterpret network traffic, potentially leading to a denial of service (DoS) condition.	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 2026-09-04 17:16:51 UTC

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

ipvs: use parsed transport offset in TCP state lookup

TCP state handling reparses the skb to find the TCP header. For IPv6 it
uses sizeof(struct ipv6hdr), while the surrounding IPVS code already
parsed the packet with ip_vs_fill_iph_skb() and has the real
transport-header offset in iph.len.

This makes TCP state handling look at the wrong bytes when an IPv6
packet carries extension headers. Use the parsed transport offset passed
down from ip_vs_set_state() when reading the TCP header.

For IPv4 and for IPv6 packets without extension headers, the passed
offset matches the previous value.

Comment 1 Mauro Matteo Cascella 2026-09-08 11:29:23 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80875.mbox