In the Linux kernel, the following vulnerability has been resolved:
net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header
dev_validate_header() reads dev->hard_header_len directly when
zero-padding short link layer headers for CAP_SYS_RAWIO holders:
if (capable(CAP_SYS_RAWIO)) {
memset(ll_header + len, 0, dev->hard_header_len - len);
return true;
}
Packet send paths call dev_validate_header() on skbs whose headroom was
allocated from an earlier hard_header_len read. If the device is
reconfigured so that dev->hard_header_len increases before validation,
the memset writes past the reserved buffer, an out-of-bounds write.
This out-of-bounds write is masked in some SOCK_RAW paths today because
the same concurrent increase can first make skb_push() exceed the
reserved headroom and trigger skb_under_panic(). Remove the zero-padding
branch before making those hard_header_len reads consistent, so the
snapshot fixes do not turn a loud panic into a silent overwrite.
This path is only reached for variable length L2 protocols, where
len < hard_header_len but len >= min_header_len. No remaining in-tree
variable length L2 protocol implements header_ops->validate, and the
CAP_SYS_RAWIO bypass that zero-pads and accepts short headers has no
real value beyond allowing testing of intentionally malformed input.
Drop the CAP_SYS_RAWIO branch. The remaining reads of
dev->hard_header_len in dev_validate_header() are comparisons only and
have no memory safety impact.
net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header
dev_validate_header() reads dev->hard_header_len directly when
zero-padding short link layer headers for CAP_SYS_RAWIO holders:
if (capable(CAP_SYS_RAWIO)) {
memset(ll_header + len, 0, dev->hard_header_len - len);
return true;
}
Packet send paths call dev_validate_header() on skbs whose headroom was
allocated from an earlier hard_header_len read. If the device is
reconfigured so that dev->hard_header_len increases before validation,
the memset writes past the reserved buffer, an out-of-bounds write.
This out-of-bounds write is masked in some SOCK_RAW paths today because
the same concurrent increase can first make skb_push() exceed the
reserved headroom and trigger skb_under_panic(). Remove the zero-padding
branch before making those hard_header_len reads consistent, so the
snapshot fixes do not turn a loud panic into a silent overwrite.
This path is only reached for variable length L2 protocols, where
len < hard_header_len but len >= min_header_len. No remaining in-tree
variable length L2 protocol implements header_ops->validate, and the
CAP_SYS_RAWIO bypass that zero-pads and accepts short headers has no
real value beyond allowing testing of intentionally malformed input.
Drop the CAP_SYS_RAWIO branch. The remaining reads of
dev->hard_header_len in dev_validate_header() are comparisons only and
have no memory safety impact.
Metrics
Affected Vendors & Products
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| Vendors | Products |
|---|---|
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Linux
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Linux Kernel
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Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 03 Sep 2026 12:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-120 CWE-122 |
Thu, 03 Sep 2026 07:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header dev_validate_header() reads dev->hard_header_len directly when zero-padding short link layer headers for CAP_SYS_RAWIO holders: if (capable(CAP_SYS_RAWIO)) { memset(ll_header + len, 0, dev->hard_header_len - len); return true; } Packet send paths call dev_validate_header() on skbs whose headroom was allocated from an earlier hard_header_len read. If the device is reconfigured so that dev->hard_header_len increases before validation, the memset writes past the reserved buffer, an out-of-bounds write. This out-of-bounds write is masked in some SOCK_RAW paths today because the same concurrent increase can first make skb_push() exceed the reserved headroom and trigger skb_under_panic(). Remove the zero-padding branch before making those hard_header_len reads consistent, so the snapshot fixes do not turn a loud panic into a silent overwrite. This path is only reached for variable length L2 protocols, where len < hard_header_len but len >= min_header_len. No remaining in-tree variable length L2 protocol implements header_ops->validate, and the CAP_SYS_RAWIO bypass that zero-pads and accepts short headers has no real value beyond allowing testing of intentionally malformed input. Drop the CAP_SYS_RAWIO branch. The remaining reads of dev->hard_header_len in dev_validate_header() are comparisons only and have no memory safety impact. | |
| Title | net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-03T08:21:48.924Z
Reserved: 2026-08-26T14:34:25.789Z
Link: CVE-2026-80731
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-03T13:06:11.707
Modified: 2026-09-03T13:06:11.707
Link: CVE-2026-80731
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-09-03T12:30:04Z