CVE-2024-49855Network attack vector

Kernel memory corruption via NBD completion race

Published Oct 21, 2024 · Updated Aug 5, 2026

Use-after-free in the Linux kernel NBD client allows remote attackers to corrupt kernel memory through timed server replies. nbd_requeue_cmd() requeues a timed-out request without first clearing NBD_CMD_INFLIGHT under cmd->lock, allowing normal completion to race with reuse of the request. An existing NBD session to a malicious or compromised server is required; repeated timed replies can disclose or overwrite kernel memory and crash or hang the host.

CVSS severity9.8
Critical
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel NBD client allows remote attackers to corrupt kernel memory through timed server replies. nbd_requeue_cmd() requeues a timed-out request without first clearing NBD_CMD_INFLIGHT under cmd->lock, allowing normal completion to race with reuse of the request. An existing NBD session to a malicious or compromised server is required; repeated timed replies can disclose or overwrite kernel memory and crash or hang the host.

The record

CVE
CVE-2024-49855
Published
Oct 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 21, 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=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <5236ada8ebbd9e7461f17477357582f5be4f46f7
  2. Affected versionversion=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <6e73b946a379a1dfbb62626af93843bdfb53753d
  3. Affected versionversion=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <9a74c3e6c0d686c26ba2aab66d15ddb89dc139cc
  4. Affected versionversion=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <9c25faf72d780a9c71081710cd48759d61ff6e9b
  5. Affected versionversion=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <c9ea57c91f03bcad415e1a20113bdb2077bcf990
  6. Affected versionversion=5.17.15 <5.18
  7. Affected versionversion=5171ef20bae852ff38f4cfdb368bcdcc744776d0
  8. Affected versionversion=5.18.4 <5.19
  9. Affected versionversion=5.19
  10. Affected versionversion=cdf62c535a9bfd5ff0eef4b91669da39d8abc0c3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <5236ada8ebbd9e7461f17477357582f5be4f46f7; version=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <6e73b946a379a1dfbb62626af93843bdfb53753d; version=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <9a74c3e6c0d686c26ba2aab66d15ddb89dc139cc; version=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <9c25faf72d780a9c71081710cd48759d61ff6e9b; version=2895f1831e911ca87d4efdf43e35eb72a0c7e66e <c9ea57c91f03bcad415e1a20113bdb2077bcf990; version=5.17.15 <5.18; version=5171ef20bae852ff38f4cfdb368bcdcc744776d0; version=5.18.4 <5.19; version=5.19; version=cdf62c535a9bfd5ff0eef4b91669da39d8abc0c3

Published CVSS scores

7.3SUSECVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
7.0SUSECVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
9.8Linux kernel CVE teamCVSS: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.

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

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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