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Vulnerability · Published Oct 18, 2026 · Assigned by Linux

CVE-2026-98621net: gue: reject invalid REMCSUM offsets

Unrated

In plain English

A security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS )–Not rated
Exploit odds (30 days)0.2%top 87.9% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

In 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.190-1DEBIAN-CVE-2026-98621
Debian:13linux6.12.113-1DEBIAN-CVE-2026-98621
Debian:14linux7.2.9-1DEBIAN-CVE-2026-98621
Debian:12linux-6.126.12.113-1~deb12u1DEBIAN-CVE-2026-98621
Ubuntu:22.04:LTSlinux5.15.0-202.212UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinuxno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux7.0.0-42.42UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-aws5.15.0-1119.126UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-aws7.0.0-1016.17UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-aws-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-aws-7.0no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure5.15.0-1125.134UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-7.0no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1124.133UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-fde-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-azure-fde-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-fde-7.0no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-gcp5.15.0-1120.130UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-gcp7.0.0-1016.18UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-gcp-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-gcp-7.0no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-gke5.15.0-1115.121UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1102.110UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-hwe-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-42.42~24.04.1UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-ibm5.15.0-1113.117UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-ibm7.0.0-1017.17UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-ibm-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1114.120UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-kvm5.15.0-1111.116UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-197.207UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1114.115UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-nvidia-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-nvidia-7.0no fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-nvidia-bosno fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-nvidia-lowlatencyno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1070.72UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-nvidia-tegrano fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1059.59UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1017.17UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-oracle5.15.0-1116.122UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-oracle7.0.0-1015.16UBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-oracle-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-oracle-7.0no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-98621
Ubuntu:26.04:LTSlinux-riscv7.0.0-42.42.1UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-riscv-6.8no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-42.42.1~24.04.1UBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-vmwareno fix listedUBUNTU-CVE-2026-98621
Ubuntu:24.04:LTSlinux-xilinxno fix listedUBUNTU-CVE-2026-98621
Ubuntu:22.04:LTSlinux-xilinx-zynqmpno fix listedUBUNTU-CVE-2026-98621

Affected products (as reported)

VendorProductVersions
Linux Linux fe881ef11cf0220f118816181930494d484c4883 – before 4b9bc21b2396c396d88dd909caaf73d5be6ff593fe881ef11cf0220f118816181930494d484c4883 – before 43efb1f997e976f386aa89716f55870cd2cff9adfe881ef11cf0220f118816181930494d484c4883 – before 1eeec0c51fd5598da44080ed96bbd9880021c28bfe881ef11cf0220f118816181930494d484c4883 – before 1d664be4ca49d1696e85239236f4988dfc4653c3fe881ef11cf0220f118816181930494d484c4883 – before 97f907203321eee2cc9132d5c9eb47698fb41d35fe881ef11cf0220f118816181930494d484c4883 – before 40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57ffe881ef11cf0220f118816181930494d484c4883 – before c20f755338ca234e523dfc943719f194dfc1f903fe881ef11cf0220f118816181930494d484c4883 – before 2566866fc30965d915d0b52b5c3323b362619f0e
Linux Linux 4.0

References