CVE-2026-31628

Cross-thread data disclosure via stale divider results

Published Apr 24, 2026 · Updated Apr 24, 2026

Information disclosure in Linux Kernel on Zen 1 CPUs allows local users to read another thread's partial hardware-divider results. On Zen 1, the hardware divider retains partial results from earlier operations, while the x86 AMD CPU setup leaves the protective chicken bit unset. A low-privileged thread scheduled on an affected system can recover cross-thread computational residue without user interaction.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Linux Kernel on Zen 1 CPUs allows local users to read another thread's partial hardware-divider results. On Zen 1, the hardware divider retains partial results from earlier operations, while the x86 AMD CPU setup leaves the protective chicken bit unset. A low-privileged thread scheduled on an affected system can recover cross-thread computational residue without user interaction.

The record

CVE
CVE-2026-31628
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0548529af20e68c6552817834b766646dd3bd7a7
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1272cfedf4cd1019ddf583917a99b62f2d3645bb
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <546785c719418c6166834a47e372a88f5f7ae893
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <91f02726b2203b71545713ecb7fb006e60a2d66f
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ad17f07e95e6e8505e2153e5b391f0d27eacce25
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b731aca06387b195058a9f6449a03b62efa1bd10
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e6af5286efe5a56128b34032572c9ce9ebeccda3
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ed7a3a246309ccc807238f1b4f159ee6d37ff9c4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0548529af20e68c6552817834b766646dd3bd7a7; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1272cfedf4cd1019ddf583917a99b62f2d3645bb; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <546785c719418c6166834a47e372a88f5f7ae893; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <91f02726b2203b71545713ecb7fb006e60a2d66f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ad17f07e95e6e8505e2153e5b391f0d27eacce25; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b731aca06387b195058a9f6449a03b62efa1bd10; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e6af5286efe5a56128b34032572c9ce9ebeccda3; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ed7a3a246309ccc807238f1b4f159ee6d37ff9c4

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Oracle LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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