GHSA-2CJW-PHMM-3745
Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-18 18:31In the Linux kernel, the following vulnerability has been resolved:
net: gue: reject invalid REMCSUM offsets
The REMCSUM option carries an absolute checksum start and checksum field offset. gue_remcsum() passes them to skb_remcsum_process(), whose partial path stores offset - start in the u16 skb->csum_offset variable. If offset is less than start, this underflows.
A forwarded packet can retain CHECKSUM_PARTIAL and reach a NETIF_F_HW_CSUM driver which trusts the metadata, leading skb_copy_and_csum_dev() to write two bytes about 64 KiB beyond the destination buffer.
Reject reversed tuples in validate_gue_flags(), after the existing length validation, so all GUE parsers enforce the ordering in one place.
{
"affected": [],
"aliases": [
"CVE-2026-98621"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-18T16:17:14Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: gue: reject invalid REMCSUM offsets\n\nThe REMCSUM option carries an absolute checksum start and checksum field\noffset. gue_remcsum() passes them to skb_remcsum_process(), whose\npartial path stores offset - start in the u16 skb-\u003ecsum_offset variable.\nIf offset is less than start, this underflows.\n\nA forwarded packet can retain CHECKSUM_PARTIAL and reach a NETIF_F_HW_CSUM\ndriver which trusts the metadata, leading skb_copy_and_csum_dev() to write\ntwo bytes about 64 KiB beyond the destination buffer.\n\nReject reversed tuples in validate_gue_flags(), after the existing length\nvalidation, so all GUE parsers enforce the ordering in one place.",
"id": "GHSA-2cjw-phmm-3745",
"modified": "2026-10-18T18:31:57Z",
"published": "2026-10-18T18:31:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98621"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1d664be4ca49d1696e85239236f4988dfc4653c3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1eeec0c51fd5598da44080ed96bbd9880021c28b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2566866fc30965d915d0b52b5c3323b362619f0e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/43efb1f997e976f386aa89716f55870cd2cff9ad"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4b9bc21b2396c396d88dd909caaf73d5be6ff593"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/97f907203321eee2cc9132d5c9eb47698fb41d35"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c20f755338ca234e523dfc943719f194dfc1f903"
}
],
"schema_version": "1.4.0",
"severity": []
}
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