CVE-2026-90151Network attack vector

Remote code execution via stale NFSv4 callback pointer

Published Sep 17, 2026 · Updated Sep 18, 2026

Use-after-free in the Linux NFSv4 client allows remote attackers to execute code via a crafted callback identifier. A failed client initialization frees nfs_client without removing its cb_ident_idr entry, so a later callback lookup increments and dereferences a stale pointer. A malicious NFSv4.0 server can force the post-publication failure and submit the identifier without victim credentials or interaction, enabling kernel memory compromise or a crash.

CVSS severity9.8
Critical
EPSS probability0.74%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux NFSv4 client allows remote attackers to execute code via a crafted callback identifier. A failed client initialization frees nfs_client without removing its cb_ident_idr entry, so a later callback lookup increments and dereferences a stale pointer. A malicious NFSv4.0 server can force the post-publication failure and submit the identifier without victim credentials or interaction, enabling kernel memory compromise or a crash.

The record

CVE
CVE-2026-90151
Published
Sep 17, 2026
Updated
Sep 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 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=2.6.38
  2. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <3f2387e8bfbc4efda5d77c3a11a028d0a119c48f
  3. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <5891c03e150920618db0e9c4ea2d772abacdcfd1
  4. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <68c721391b761dbe38d5b0094d2bb6e8489ad92b
  5. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <7c4812eb96bdcafb31a65b12f2aa96659429d1d4
  6. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <80b1c3d5a881f7d9081aa9f46da9742878a0f893
  7. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <9bfdd0f591307b5198826a0e7a5b2f35f87acd2d
  8. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <d05c2007b3d84ccba11dc6e9cb3202768cc72f14
  9. Affected versionversion=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <fc95ca82d5ae598c428ab5a00ae69f8526d59371

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.38; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <3f2387e8bfbc4efda5d77c3a11a028d0a119c48f; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <5891c03e150920618db0e9c4ea2d772abacdcfd1; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <68c721391b761dbe38d5b0094d2bb6e8489ad92b; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <7c4812eb96bdcafb31a65b12f2aa96659429d1d4; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <80b1c3d5a881f7d9081aa9f46da9742878a0f893; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <9bfdd0f591307b5198826a0e7a5b2f35f87acd2d; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <d05c2007b3d84ccba11dc6e9cb3202768cc72f14; version=f4eecd5da3422e82e88e36c33cbd2595eebcacb1 <fc95ca82d5ae598c428ab5a00ae69f8526d59371

Published CVSS scores

5.2Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H
9.8Linux CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1203Exploitation for Client Execution

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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