CVE-2026-98621
Status: ReceivedUnscored—
Severity—Unscored
Exploitation probability0.21 %higher than 11% of CVEs
Active exploitationNonot in the CISA catalog
Public exploitNot knownno public code found
In 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.
CVSS
NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.21 %
- Percentile among all scored CVEs
- 11
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
References
Show 8 references
- https://git.kernel.org/stable/c/1d664be4ca49d1696e85239236f4988dfc4653c3
- https://git.kernel.org/stable/c/1eeec0c51fd5598da44080ed96bbd9880021c28b
- https://git.kernel.org/stable/c/2566866fc30965d915d0b52b5c3323b362619f0e
- https://git.kernel.org/stable/c/40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f
- https://git.kernel.org/stable/c/43efb1f997e976f386aa89716f55870cd2cff9ad
- https://git.kernel.org/stable/c/4b9bc21b2396c396d88dd909caaf73d5be6ff593
- https://git.kernel.org/stable/c/97f907203321eee2cc9132d5c9eb47698fb41d35
- https://git.kernel.org/stable/c/c20f755338ca234e523dfc943719f194dfc1f903
Raw JSON (NVD)
Show
{
"id": "CVE-2026-98621",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "4b9bc21b2396c396d88dd909caaf73d5be6ff593",
"versionType": "git"
},
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "43efb1f997e976f386aa89716f55870cd2cff9ad",
"versionType": "git"
},
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "1eeec0c51fd5598da44080ed96bbd9880021c28b",
"versionType": "git"
},
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "1d664be4ca49d1696e85239236f4988dfc4653c3",
"versionType": "git"
},
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "97f907203321eee2cc9132d5c9eb47698fb41d35",
"versionType": "git"
},
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f",
"versionType": "git"
},
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "c20f755338ca234e523dfc943719f194dfc1f903",
"versionType": "git"
},
{
"status": "affected",
"version": "fe881ef11cf0220f118816181930494d484c4883",
"lessThan": "2566866fc30965d915d0b52b5c3323b362619f0e",
"versionType": "git"
}
],
"programFiles": [
"include/net/gue.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.0"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.271",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.222",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.55",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.9",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"include/net/gue.h"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:14.997",
"references": [
{
"url": "https://git.kernel.org/stable/c/1d664be4ca49d1696e85239236f4988dfc4653c3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/1eeec0c51fd5598da44080ed96bbd9880021c28b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/2566866fc30965d915d0b52b5c3323b362619f0e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/43efb1f997e976f386aa89716f55870cd2cff9ad",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/4b9bc21b2396c396d88dd909caaf73d5be6ff593",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/97f907203321eee2cc9132d5c9eb47698fb41d35",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c20f755338ca234e523dfc943719f194dfc1f903",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "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->csum_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."
}
],
"lastModified": "2026-10-19T10:19:26.217",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}