Out-of-bounds Read Affecting kernel-kvmsmall package, versions <6.12.0-160000.37.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.12% (3rd percentile)

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  • Snyk IDSNYK-SLES1600-KERNELKVMSMALL-19316509
  • published27 Aug 2026
  • disclosed11 Aug 2026

Introduced: 11 Aug 2026

NewCVE-2026-46130  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

Upgrade SLES:16.0.0 kernel-kvmsmall to version 6.12.0-160000.37.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-kvmsmall package and not the kernel-kvmsmall package as distributed by SLES. See How to fix? for SLES:16.0.0 relevant fixed versions and status.

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

dm-verity-fec: fix reading parity bytes split across blocks (take 3)

fec_decode_bufs() assumes that the parity bytes of the first RS codeword it decodes are never split across parity blocks.

This assumption is false. Consider v->fec->block_size == 4096 && v->fec->roots == 17 && fio->nbufs == 1, for example. In that case, each call to fec_decode_bufs() consumes v->fec->roots * (fio->nbufs << DM_VERITY_FEC_BUF_RS_BITS) = 272 parity bytes.

Considering that the parity data for each message block starts on a block boundary, the byte alignment in the parity data will iterate through 272*i mod 4096 until the 3 parity blocks have been consumed. On the 16th call (i=15), the alignment will be 4080 bytes into the first block. Only 16 bytes remain in that block, but 17 parity bytes will be needed. The code reads out-of-bounds from the parity block buffer.

Fortunately this doesn't normally happen, since it can occur only for certain non-default values of fec_roots and when the maximum number of buffers couldn't be allocated due to low memory. For example with block_size=4096 only the following cases are affected:

fec_roots=17: nbufs in [1, 3, 5, 15]
fec_roots=19: nbufs in [1, 229]
fec_roots=21: nbufs in [1, 3, 5, 13, 15, 39, 65, 195]
fec_roots=23: nbufs in [1, 89]

Regardless, fix it by refactoring how the parity blocks are read.

CVSS Base Scores

version 3.1