CVE-2023-6240Network attack vector

Ciphertext decryption via RSA timing oracle

Published Feb 4, 2024 · Updated Nov 8, 2025

Timing leakage in Linux kernel RSA decryption on affected Red Hat Enterprise Linux releases allows remote attackers to decrypt ciphertexts. The kernel RSA private-key operation exposes input-dependent timing differences that form a Bleichenbacher oracle. Reachability requires a network service that delegates automated RSA private-key operations to the kernel; repeated chosen-ciphertext queries can recover plaintext or forge signatures.

CVSS severity6.5
Medium
EPSS probability0.97%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Timing leakage in Linux kernel RSA decryption on affected Red Hat Enterprise Linux releases allows remote attackers to decrypt ciphertexts. The kernel RSA private-key operation exposes input-dependent timing differences that form a Bleichenbacher oracle. Reachability requires a network service that delegates automated RSA private-key operations to the kernel; repeated chosen-ciphertext queries can recover plaintext or forge signatures.

The record

CVE
CVE-2023-6240
Published
Feb 4, 2024
Updated
Nov 8, 2025
Vendor
Red Hat
Product
Red Hat Enterprise Linux 8
Classifications
CWE-203, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.0 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.2 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.

Published CVSS scores

6.5Red Hat, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy
T1190Exploit Public-Facing Application

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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