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CVE-2026-80731

net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.2.81, 3.17, 4.2, 4.5, 4.6, and 7 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From b5518429e70cd783b8ca52335456172c1a0589f6 · fixed in 53fd7f912c0877647d6a1e1877f5ea8535ee0b4a; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in 8fc9816404166a90ed8d544dc52482fafffb6d9f; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in b0f92a5731dc82556a9ae005cc35f71ab136307b; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in 99df6b7a713f96eda206680d100b76e15f9d9b69; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in 74e035f07f53feca09e2352e77fccb09cad5e208; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in dbb30dc943a93e083f1e531bfdc6779e57de40d0; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in fc902f52a02298c7432b2334c0c82a2885a1a8b6; From 2793a23aacbd754dbbb5cb75093deb7e4103bace · fixed in 3b9a324e646d3657a8d9806dfbfe4f3e4066e882; From 3.2.80 · fixed in 3.2.81; From 3.16.36 · fixed in 3.17; From 4.1.28 · fixed in 4.2; From 4.4.8 · fixed in 4.5; From 4.5.2 · fixed in 4.6

  • Linux Linux

    4.6

  • KernelLinux

    fixed in 3.2.81; From 3.3.0 · fixed in 5.10.265; From 4.6.0 · fixed in 5.15.216; From 5.11.0 · fixed in 6.1.183; From 5.16.0 · fixed in 6.6.152; From 6.2.0 · fixed in 6.12.104; From 6.7.0 · fixed in 6.18.45; From 6.13.0 · fixed in 7.1.9

References 9

git.kernel.org