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CVE-2026-80731

HIGHCVSS 7.8/10EPSS 0.24%

Last modified

CVE-2026-80731 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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(). EPSS estimates a 0.24% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
0.24%

15.4th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= b5518429e70cd783b8ca52335456172c1a0589f6, < 53fd7f912c0877647d6a1e1877f5ea8535ee0b4a; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < 8fc9816404166a90ed8d544dc52482fafffb6d9f; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < b0f92a5731dc82556a9ae005cc35f71ab136307b; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < 99df6b7a713f96eda206680d100b76e15f9d9b69; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < 74e035f07f53feca09e2352e77fccb09cad5e208; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < dbb30dc943a93e083f1e531bfdc6779e57de40d0; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < fc902f52a02298c7432b2334c0c82a2885a1a8b6; >= 2793a23aacbd754dbbb5cb75093deb7e4103bace, < 3b9a324e646d3657a8d9806dfbfe4f3e4066e882; f58a6c08ebdfa978178bbca78c2ba744a2665912; 1df16498dfd0d5a129bdf2982d9a08df73e8923d; 8b8d278aa4de9335682bbd4a3bb619af015c859e; 6804052fa9d86e9a512c88b24a5debbfc1a490fc; >= 3.2.80, < 3.2.81; >= 3.16.36, < 3.17; >= 4.1.28, < 4.2; >= 4.4.8, < 4.5; >= 4.5.2, < 4.6
LinuxLinux4.6

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-80731?
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.
How severe is CVE-2026-80731?
CVE-2026-80731 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.
How do I fix CVE-2026-80731?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST