CVE-2026-72349: netfilter: xt_rateest: fix u64 truncation in xt_rateest_mt()
In the Linux kernel, the following vulnerability has been resolved:
netfilter: xtrateest: fix u64 truncation in xtrateestmt()
On links faster than ~34 Gbps, where byte rate may exceed 2^32-1 (~ 4.3 GBps), the comparison result becomes incorrect because the truncated value no longer reflects the actual estimator rate.
Fix by changing the local variables to u64.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1117.124~20.04.1 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1067.68 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-147.147.1 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1064.67 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1033.38 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1062.63 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-147.147+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
In the Linux kernel netfilter xt_rateest_mt() implementation, change the local variables used for byte-rate comparison to u64 to prevent truncation above 2^32-1.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-72349?
CVE-2026-72349 has a risk rating of 12, indicating a high severity level.
How does CVE-2026-72349 affect Linux kernel performance?
CVE-2026-72349 can cause incorrect comparison results on high-speed links, affecting rate calculations.
What versions of the Linux kernel are affected by CVE-2026-72349?
CVE-2026-72349 affects versions of the Linux kernel that utilize the xt_rateest module on links exceeding ~34 Gbps.
How do I fix CVE-2026-72349?
To fix CVE-2026-72349, update your Linux kernel to the latest version where the vulnerability has been resolved.
What is the primary nature of the issue in CVE-2026-72349?
CVE-2026-72349 involves a u64 truncation issue in the xt_rateest_mt() function, leading to incorrect traffic rate comparisons.