CVE-2024-27354Network attack vector

CPU exhaustion via unbounded primality testing

Published Mar 1, 2024 · Updated Apr 22, 2025

Denial of service in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36 allows attackers to exhaust CPU with a malformed certificate. Certificate parsing passes an attacker-sized prime to BigInteger::isPrime(), which performs primality testing without a bit-length limit. Exposure requires an application to process attacker-controlled certificates; exploitation ties up CPU without reported data disclosure or modification.

CVSS severity8.7
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36 allows attackers to exhaust CPU with a malformed certificate. Certificate parsing passes an attacker-sized prime to BigInteger::isPrime(), which performs primality testing without a bit-length limit. Exposure requires an application to process attacker-controlled certificates; exploitation ties up CPU without reported data disclosure or modification.

The record

CVE
CVE-2024-27354
Published
Mar 1, 2024
Updated
Apr 22, 2025
Vendor
phpseclib
Product
phpseclib
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.0.23
  2. Affected versionversion=0 <2.0.47
  3. Affected versionversion=0 <3.0.36

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

phpseclib · phpseclibversion=0 <1.0.23; version=0 <2.0.47; version=0 <3.0.36

Published CVSS scores

7.5phpseclibCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA: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 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

CWE-400Uncontrolled Resource Consumption
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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