UBUNTU-CVE-2026-80603: Critical severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfconntrackirc: fix parsedcc() off-by-one OOB read parsedcc() treats dataend as an inclusive end pointer, but its only caller passes datalimit = ibptr + datalen, which points one past the last valid byte. The newline search loop iterates while tmp <= dataend, so when no newline is present, tmp is read at tmp == dataend, one byte beyond the region filled by skbheaderpointer(). ircbuffer is kmalloc'd as MAXSEARCHSIZE + 1 bytes and datalen is capped at MAXSEARCHSIZE, so the stray read does not fault. The byte is uninitialized or stale; if it contains an ASCII digit, simplestrtoul will consume it and produce a wrong DCC IP or port in the conntrack expectation. The extra allocation byte is also a fragile guard: if the cap or allocation size changes, this becomes a real out-of-bounds read. Change the loop and its post-loop check to use strict less-than, consistent with the caller's exclusive-end convention. Update the function comment accordingly.
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-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-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-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-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 netfilter nf_conntrack_irc parse_dcc(), change the newline-search loop and its post-loop check from inclusive (<=) to strict less-than (<) comparisons, consistent with the caller's exclusive-end data_limit convention, and update the function comment accordingly.
Event History
Frequently Asked Questions
What traffic must reach the affected code path?
The issue is in the IRC conntrack parser's handling of DCC data. It is triggered when parse_dcc() processes data with no newline before the supplied data limit, causing the parser to inspect one byte past the valid buffered region.
What is the practical impact of the out-of-bounds read described here?
The extra byte is within the current allocation but may contain uninitialized or stale data. If that byte is an ASCII digit, the parser can consume it and create a conntrack expectation with an incorrect DCC IP address or port; the issue could become a true out-of-bounds read if the buffer cap or allocation changes.