CVE-2026-98621

NameCVE-2026-98621
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: gue: reject invalid REMCSUM offsets The REMCSUM option carries an absolute checksum start and checksum field offset. gue_remcsum() passes them to skb_remcsum_process(), whose partial path stores offset - start in the u16 skb->csum_offset variable. If offset is less than start, this underflows. A forwarded packet can retain CHECKSUM_PARTIAL and reach a NETIF_F_HW_CSUM driver which trusts the metadata, leading skb_copy_and_csum_dev() to write two bytes about 64 KiB beyond the destination buffer. Reject reversed tuples in validate_gue_flags(), after the existing length validation, so all GUE parsers enforce the ordering in one place.
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-4850-1

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)6.12.115-2fixed
forky7.2.15-1fixed
sid7.3.3-1fixed
linux-6.12 (PTS)bookworm (security)6.12.115-2~deb12u1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebookworm6.1.190-1
linuxsourcetrixie6.12.113-1
linuxsource(unstable)7.2.9-1
linux-6.12sourcebookworm6.12.113-1~deb12u1DLA-4850-1

Notes

https://git.kernel.org/linus/2566866fc30965d915d0b52b5c3323b362619f0e (7.3-rc5)

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