Bug 2532185 (CVE-2026-89565)

Summary: CVE-2026-89565 kernel: ipip: fix skb leak in collect_md mode when metadata_dst allocation fails
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: 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   
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Doc Text:
A flaw was found in the Linux kernel's IP over IP (ipip) tunnel driver. When operating in collect_md mode, the ipip_tunnel_rcv() function fails to free a network packet buffer (skb) if the metadata_dst allocation fails. This oversight leads to a memory leak. A local attacker could potentially exploit this vulnerability to exhaust system memory, resulting in a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 21:11:41 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ipip: fix skb leak in collect_md mode when metadata_dst allocation fails

In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb
when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and
mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv()
and tunnelmpls4_rcv() read the zero return as "the packet has been
consumed" and do not free it either. The skb is leaked.

The other tunnel drivers all dispose of the packet at this point:
ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return
PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0.

Jump to the existing drop label instead. It frees the skb and still
returns 0, so the packet keeps being reported as consumed, which is what
we want here: the outer header has already been pulled, and neither the
remaining handlers nor an ICMP unreachable have any use for it.

Triggering this needs an ipip or mplsip tunnel in collect_md mode and an
atomic allocation failure, which is why it has gone unnoticed.
Comment 1 Keith Grant 2026-09-18 16:04:52 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89565.mbox