CVE-2024-2408Public exploitNetwork attack vector

Ciphertext decryption via PKCS1 timing oracle

Published Jun 9, 2024 · Updated Mar 21, 2025

Observable timing discrepancy in PHP 8.1.28 and earlier, 8.2.19 and earlier, and 8.3.7 and earlier allows remote attackers to decrypt data. openssl_private_decrypt with default PKCS#1 v1.5 padding processes valid and invalid messages in measurably different times, creating a decryption oracle. Exploitation requires repeated chosen-ciphertext measurements against an application exposing this RSA path and also enables signature forgery with the exposed key.

CVSS severity5.9
Medium
EPSS probability1.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable timing discrepancy in PHP 8.1.28 and earlier, 8.2.19 and earlier, and 8.3.7 and earlier allows remote attackers to decrypt data. openssl_private_decrypt with default PKCS#1 v1.5 padding processes valid and invalid messages in measurably different times, creating a decryption oracle. Exploitation requires repeated chosen-ciphertext measurements against an application exposing this RSA path and also enables signature forgery with the exposed key.

The record

CVE
CVE-2024-2408
Published
Jun 9, 2024
Updated
Mar 21, 2025
Vendor
The PHP Group
Product
PHP
Classifications
CWE-327, CWE-385, CWE-208, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 21, 2025Record 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=8.1.0 <8.1.29
  2. Affected versionversion=8.1.* <8.1.29
  3. Affected versionversion=8.2.0 <8.2.20
  4. Affected versionversion=8.2.* <8.2.20
  5. Affected versionversion=8.3.0 <8.3.8
  6. Affected versionversion=8.3.* <8.3.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The PHP Group · PHPversion=8.1.0 <8.1.29; version=8.1.* <8.1.29; version=8.2.0 <8.2.20; version=8.2.* <8.2.20; version=8.3.0 <8.3.8; version=8.3.* <8.3.8
Fedora Project · Fedora Linuxversion=40

Published CVSS scores

5.9CISACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
5.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/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 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 exploitPublished

Weakness, pattern, technique

CWE-327Use of a Broken or Risky Cryptographic Algorithm
CWE-385Covert Timing Channel
CWE-208Observable Timing Discrepancy
T1190Exploit Public-Facing Application

Public exploit references

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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