CVE-2026-98306

NameCVE-2026-98306
DescriptionIn the Linux kernel, the following vulnerability has been resolved: seg6: set IPSKB_L3SLAVE from IP6SKB_L3SLAVE on IPIP decapsulation When an SRv6 packet arrives on an interface enslaved to a VRF, vrf_ip6_rcv() sets IP6SKB_L3SLAVE in IP6CB, but decap_and_validate() has never set IPSKB_L3SLAVE in IPCB. The bit stayed clear in the common case, and with CONFIG_IPV6_MIP6 the leftover frag_max_size of a reassembled outer packet could even set it, with no VRF involved. Commit 44930446dde4 ("ipv6: seg6: clear IPv4 control block on IPIP decapsulation") then made the unreliable bit reliably clear. The effect of the missing flag is visible with End.DX4 when a delivery to a local address of the node reaches the socket lookup. For example, a UDP socket bound to the enslaved ingress interface does not receive any of the decapsulated packets, while an unbound socket outside the VRF does. This contradicts Documentation/networking/vrf.rst: by default the scope of an unbound UDP or TCP socket is limited to the default VRF. Set IPSKB_L3SLAVE for IPv4 in decap_and_validate(), which already does the same for IPv6. The socket lookup then matches the decapsulated packet like any other packet received on that enslaved interface. Such a packet matches an unbound UDP or TCP socket only when udp_l3mdev_accept or tcp_l3mdev_accept is set.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-4841-1, DLA-4850-1, DSA-6568-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bookworm6.1.176-1vulnerable
bookworm (security)6.1.190-1fixed
trixie6.12.107-1vulnerable
trixie (security)6.12.113-1fixed
forky, sid7.2.12-1fixed
linux-6.12 (PTS)bookworm (security)6.12.113-1~deb12u1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebookworm6.1.190-1DLA-4841-1
linuxsourcetrixie6.12.113-1DSA-6568-1
linuxsource(unstable)7.2.8-1
linux-6.12sourcebookworm6.12.113-1~deb12u1DLA-4850-1

Notes

https://git.kernel.org/linus/7616242a2b37883f7322aaa1d2bd6cd0fed28315 (7.3-rc4)

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