CVE-2026-72392: ipv6: fib6: fix NULL deref in fib6_walk_continue() on multi-batch dump
In the Linux kernel, the following vulnerability has been resolved:
ipv6: fib6: fix NULL deref in fib6walkcontinue() on multi-batch dump
inet6dumpfib() saves its progress in cb->args[1] as a positional index within the current hash chain. Between batches, a concurrent fib6newtable() can insert a new table at the chain head, shifting all existing entries. The saved index then lands on a different table, causing fib6dumptable() to set w->root to the wrong table while w->node still points into the previous one. fib6walkcontinue() dereferences w->node->parent (NULL) and panics:
BUG: kernel NULL pointer dereference, address: 0000000000000008 RIP: 0010:fib6walkcontinue+0x6e/0x170 Call Trace: <TASK> fib6dumptable.isra.0+0xc5/0x240 inet6dumpfib+0xf6/0x420 rtnldumpit+0x30/0xa0 netlinkdump+0x15b/0x460 netlinkrecvmsg+0x1d6/0x2a0 sysrecvmsg+0x17a/0x190
Fix by storing tb->tb6id in cb->args[1] instead of a positional index. On resume, skip entries until the id matches; a concurrent head-insert can never match the saved id, so the walker always resumes on the correct table.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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Fixed in 6.6.152.1-1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-147.147 - 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-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - 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-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-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
In inet6_dump_fib(), store tb->tb6_id in cb->args[1] instead of a positional index, and on resume skip entries until the saved table ID matches.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-72392?
CVE-2026-72392 has a risk score of 37, indicating a moderate level of severity.
How do I fix CVE-2026-72392?
To fix CVE-2026-72392, ensure your Linux kernel is updated to the version that includes the patch for this vulnerability.
What type of vulnerability is CVE-2026-72392?
CVE-2026-72392 is classified as a Null Pointer Dereference vulnerability in the Linux kernel.
When was CVE-2026-72392 published?
CVE-2026-72392 was published on August 15, 2026.
What function is affected by CVE-2026-72392?
CVE-2026-72392 affects the fib6_walk_continue() function related to the inet6_dump_fib() operation in the Linux kernel.