Incorrect Calculation of Buffer Size Affecting kernel-modules-internal package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.21% (11th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELMODULESINTERNAL-21031578
  • published16 Oct 2026
  • disclosed17 Sept 2026

Introduced: 17 Sep 2026

NewCVE-2026-90160  (opens in a new tab)
CWE-131  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:8 kernel-modules-internal.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-modules-internal package and not the kernel-modules-internal package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

lwt_bpf: Restore reserved headroom after xmit program

ip_finish_output2() expands an skb to LL_RESERVED_SPACE(dev) before LWT xmit. An LWT_XMIT BPF program can then modify the skb head and still return BPF_OK, so bpf_xmit() rechecks the remaining headroom before the skb continues to neighbour output.

That recheck uses dst->dev->hard_header_len. This is not enough for the neighbour cached-header path: neigh_hh_output() copies the cached hardware header using the aligned hh_cache size, HH_DATA_MOD for short headers or HH_DATA_ALIGN(hh_len) otherwise.

On Ethernet, hard_header_len is 14 but the cached copy needs 16 bytes. If an LWT_XMIT BPF program calls bpf_skb_change_head(skb, 1, 0), the skb can still have 15 bytes of headroom after the program. The existing check accepts that, after which neigh_hh_output() hits its headroom warning and drops the skb.

Use LL_RESERVED_SPACE(dst->dev) in the post-BPF headroom check to match the reservation made before LWT xmit.

CVSS Base Scores

version 3.1