EUVD-2026-67479
GHSA-66q8-v4rr-393c
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Reached only when the nf_conntrack_irc helper is active and no newline is present, so AC:H; no data is disclosed to the attacker (C:N), at worst a corrupted conntrack expectation (I:L), no crash (A:N).
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
Lifecycle Timeline
5DescriptionCVE.org
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.
AnalysisAI
Out-of-bounds read in the Linux kernel's netfilter nf_conntrack_irc connection-tracking helper (parse_dcc) allows a one-byte stale read past the IRC DCC parse buffer, potentially producing an incorrect DCC IP or port in the resulting conntrack expectation. The flaw stems from parse_dcc() treating data_end as an inclusive pointer while its caller passes an exclusive one-past-the-end limit; the read currently cannot fault because irc_buffer is over-allocated by one byte and datalen is capped at MAX_SEARCH_SIZE. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Requires the nf_conntrack_irc connection-tracking helper to be loaded and actively parsing IRC traffic traversing the host (typically a Linux firewall/router/NAT gateway) - on systems without this helper the vulnerable code path is never reached. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The signals conflict sharply and should be reconciled before prioritization. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patch: update to a fixed Linux kernel build for your branch - 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5, or 7.2 (or later) - via your distribution's kernel package, referencing the stable commits at git.kernel.org such as https://git.kernel.org/stable/c/abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e and the NVD entry https://nvd.nist.gov/vuln/detail/CVE-2026-80603. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify and document all Linux systems in your environment with the nf_conntrack_irc kernel helper enabled to establish the scope of affected assets. …
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Same technique Buffer Overflow
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External POC / Exploit Code
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