CVE-2026-64306

Uninitialized output via suppressed DRBG update errors

Published Jul 25, 2026 · Updated Jul 25, 2026

Incorrect error handling in Linux Kernel CTR_DRBG allows attackers to cause unspecified impact via an internal update failure. In drbg_ctr_generate(), a nonzero result from drbg_ctr_update() is replaced with zero, so the caller treats an uninitialized output buffer as successfully generated random data. Public sources do not establish attacker control over the update failure or a specific downstream security consequence.

CVSS severityUnavailable
Unscored
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect error handling in Linux Kernel CTR_DRBG allows attackers to cause unspecified impact via an internal update failure. In drbg_ctr_generate(), a nonzero result from drbg_ctr_update() is replaced with zero, so the caller treats an uninitialized output buffer as successfully generated random data. Public sources do not establish attacker control over the update failure or a specific downstream security consequence.

The record

CVE
CVE-2026-64306
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 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=3.12.44 <3.13
  2. Affected versionversion=4.1
  3. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <074db6db03a0aaa78f05ca9d4838053713796665
  4. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <23b8b188cb32e5531d0f8d3af9506f8959cb369e
  5. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <39a31ad9e2a5ed7e9c9c6f711dca96c8c8f5f26b
  6. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <75597e8774f319152744d24e0683d9393540a951
  7. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <7b03312491f9fe6ba4d60c4023e7e61d2d1fed96
  8. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <a9e886f73dd717027028bb7e3bbca93601ecdfc7
  9. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <bbbac12083eff489b35d848332f0dff311131344
  10. Affected versionversion=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <cc42fb40171c249bb859071d81b4eb007398a0bc
  11. Affected versionversion=f60b0fa8bbddde66f1d197be07120264b555c84a

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.12.44 <3.13; version=4.1; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <074db6db03a0aaa78f05ca9d4838053713796665; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <23b8b188cb32e5531d0f8d3af9506f8959cb369e; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <39a31ad9e2a5ed7e9c9c6f711dca96c8c8f5f26b; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <75597e8774f319152744d24e0683d9393540a951; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <7b03312491f9fe6ba4d60c4023e7e61d2d1fed96; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <a9e886f73dd717027028bb7e3bbca93601ecdfc7; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <bbbac12083eff489b35d848332f0dff311131344; version=cde001e4c3c3625c60b68a83eb1f1c2572dee07a <cc42fb40171c249bb859071d81b4eb007398a0bc; version=f60b0fa8bbddde66f1d197be07120264b555c84a

Published CVSS scores

No CVSS assessment is available in this record.

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)
VectorUnavailable
PrivilegesUnavailable
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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