Medium 5.5Published Jul 19, 2026

CVE-2026-63868net: garp: fix unsigned integer underflow in garp_pdu_parse_attr

Updated under an hour ago (Oct 28, 2026, 8:00 AM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: net: garp: fix unsigned integer underflow in garp_pdu_parse_attr The receive-side GARP attribute parser computes dlen with reversed operands: dlen = sizeof(*ga) - ga->len; ga->len is the on-wire attribute length and includes the GARP attribute header. For normal attributes with data, ga->len is larger than sizeof(*ga), so the subtraction underflows in unsigned arithmetic. The resulting value is later passed to garp_attr_lookup(), whose length argument is u8. After truncation, the parsed data length usually no longer matches the length stored for locally registered attributes, so received Join/Leave events are ignored. This breaks the GARP receive path for common attributes, such as GVRP VLAN registration attributes. Compute the data length as the attribute length minus the header length.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: Jul 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before 29f28172afb2ae7b31e9bf3e978396f20b381688; from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before 973cf7c433d27f4d9556d0b7c332543be7ed7a6e; from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before d8dcd14aa886b8effd83022c550669f4f262854b; from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before 74e02121be1dcc0efcd56ebdf0171d6129105659; from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before d4c86ea09ae3e63ee5aa86e941fcc38e0e39874a; from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before 04e22fefac1af3e32f245e9045382348773b5d59; from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before a11f1a671b1361f0f1278dc0041374f2730df73f; from eca9ebac651f774d8b10fce7c5d173c3c3d3394f before 16e408e607a94b646fb14a2a98422c6877ae4b3c	CNA record
linux linux_kernel linux:linux_kernel	from 2.6.27 before 5.10.259; from 5.11 before 5.15.210; from 5.16 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; from 6.19 before 7.0.13; 7.1; and 5 more ranges	NVD

References

References

https://git.kernel.org/stable/c/29f28172afb2ae7b31e9bf3e978396f20b381688	patch
https://git.kernel.org/stable/c/973cf7c433d27f4d9556d0b7c332543be7ed7a6e	patch
https://git.kernel.org/stable/c/d8dcd14aa886b8effd83022c550669f4f262854b	patch
https://git.kernel.org/stable/c/74e02121be1dcc0efcd56ebdf0171d6129105659	patch
https://git.kernel.org/stable/c/d4c86ea09ae3e63ee5aa86e941fcc38e0e39874a	patch
https://git.kernel.org/stable/c/04e22fefac1af3e32f245e9045382348773b5d59	patch
https://git.kernel.org/stable/c/a11f1a671b1361f0f1278dc0041374f2730df73f	patch
https://git.kernel.org/stable/c/16e408e607a94b646fb14a2a98422c6877ae4b3c	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.