CVE-2024-27355 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in phpseclib/phpseclib. A fix is available for phpseclib/phpseclib — see the affected versions and patch details below.
phpseclib guardrails needed on OID length
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-27355.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
phpseclib/phpseclib🐘phpseclib/phpseclib🐘phpseclib/phpseclibReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
An issue was discovered in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36. When processing the ASN.1 object identifier of a certificate, a sub identifier may be provided that leads to a denial of service (CPU consumption for decodeOID).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | phpseclib/phpseclib | ≥ 2.0.0&&< 2.0.47 | 2.0.47composer require phpseclib/phpseclib:^2.0.47 |
| 🐘Packagist | phpseclib/phpseclib | ≥ 3.0.0&&< 3.0.36 | 3.0.36composer require phpseclib/phpseclib:^3.0.36 |
| 🐘Packagist | phpseclib/phpseclib | ≥ 0.1.1&&< 1.0.23 | 1.0.23composer require phpseclib/phpseclib:^1.0.23 |
Affected Products
debian linuxdebianphpseclibphpseclibDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phpseclib/phpseclib, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update phpseclib/phpseclib to 2.0.47 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-27355 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2024-27355 in your dependencies?
Find it across Packagist, including transitive dependencies.