CVE-2021-47478Network attack vector

Kernel memory disclosure and crash via ISOFS over-read

Published May 22, 2024 · Updated Aug 5, 2026

Out-of-bounds read in Linux ISOFS allows remote attackers to disclose kernel memory or crash an NFS server via crafted filehandles. isofs_read_inode trusts a corrupted directory entry's length before reading fields beyond its allocated buffer. Remote reachability requires an ISO 9660 mount exported through NFS; otherwise, supplying a corrupted image requires local mount privileges.

CVSS severity5.5
Medium
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux ISOFS allows remote attackers to disclose kernel memory or crash an NFS server via crafted filehandles. isofs_read_inode trusts a corrupted directory entry's length before reading fields beyond its allocated buffer. Remote reachability requires an ISO 9660 mount exported through NFS; otherwise, supplying a corrupted image requires local mount privileges.

The record

CVE
CVE-2021-47478
Published
May 22, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 22, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <156ce5bb6cc43a80a743810199defb1dc3f55b7f
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6e80e9314f8bb52d9eabe1907698718ff01120f5
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <86d4aedcbc69c0f84551fb70f953c24e396de2d7
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9ec33a9b8790c212cc926a88c5e2105f97f3f57e
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <afbd40f425227e661d991757e11cc4db024e761f
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b0ddff8d68f2e43857a84dce54c3deab181c8ae1
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b2fa1f52d22c5455217b294629346ad23a744945
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e7fb722586a2936b37bdff096c095c30ca06404d
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e96a1866b40570b5950cda8602c2819189c62a48
  10. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <156ce5bb6cc43a80a743810199defb1dc3f55b7f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6e80e9314f8bb52d9eabe1907698718ff01120f5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <86d4aedcbc69c0f84551fb70f953c24e396de2d7; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9ec33a9b8790c212cc926a88c5e2105f97f3f57e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <afbd40f425227e661d991757e11cc4db024e761f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b0ddff8d68f2e43857a84dce54c3deab181c8ae1; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b2fa1f52d22c5455217b294629346ad23a744945; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e7fb722586a2936b37bdff096c095c30ca06404d; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e96a1866b40570b5950cda8602c2819189c62a48; version=2.6.12

Published CVSS scores

5.5CISA ADP VulnrichmentCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

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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