CVE-2026-80603: Linux Vulnerability (CVSS 9.1)

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read parse_dcc() treats data_end as an inclusive end pointer, but its only caller passes data_limit = ib_ptr + datalen, which points one past the last valid byte. The newline search loop iterates while tmp <= data_end, so when no newline is present, *tmp is read at tmp == data_end, one byte beyond the region filled by skb_header_pointer(). irc_buffer is kmalloc'd as MAX_SEARCH_SIZE + 1 bytes and datalen is capped at MAX_SEARCH_SIZE, so the stray read does not fault. The byte is uninitialized or stale; if it contains an ASCII digit, simple_strtoul 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.

Metrics

CVSS 3.1

9.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

0.18%

7.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 437e0a3854b3a44ec15afa9ab88ec215adf3a2fd; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 2b70f61f569bb29acb380e6f616a1bbdee15668f; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 2393f0bd7a467ad475598f3a5b9de27ca36e3037; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < aff589556ed772cb1c0c2d7b4d91ec45c0c39416; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < eeef3b81f449560653662df2dde6f6fe247c5365; >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a
Linux	Linux	2.6.12

References

Timeline

Published: Aug 28, 2026
Last Modified: Aug 29, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-80603?

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read parse_dcc() treats data_end as an inclusive end pointer, but its only caller passes data_limit = ib_ptr + datalen, which points one past the last valid byte. The newline search loop iterates while tmp <= data_end, so when no newline is present, *tmp is read at tmp == data_end, one byte beyond the region filled by skb_header_pointer(). irc_buffer is kmalloc'd as MAX_SEARCH_SIZE + 1 bytes and datalen is capped at MAX_SEARCH_SIZE, so the stray read does not fault. The byte is uninitialized or stale; if it contains an ASCII digit, simple_strtoul 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.

How severe is CVE-2026-80603?

CVE-2026-80603 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.

How do I fix CVE-2026-80603?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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