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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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Solution
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Workaround
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Sun, 18 Oct 2026 18:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-190 |
Sun, 18 Oct 2026 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | net: gue: reject invalid REMCSUM offsets | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
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Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-10-18T15:19:41.211Z
Reserved: 2026-09-25T10:25:14.360Z
Link: CVE-2026-98621
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-10-18T16:17:14.997
Modified: 2026-10-18T16:17:14.997
Link: CVE-2026-98621
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-10-18T18:30:14Z