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CVE-2025-46728

Cpp-httplib denial of service

7.5 HIGHPublic exploitEPSS 0.66%
  1. Published5 May 2025

Description

cpp-httplib is a C++ header-only HTTP/HTTPS server and client library. Prior to version 0.20.1, the library fails to enforce configured size limits on incoming request bodies when `Transfer-Encoding: chunked` is used or when no `Content-Length` header is provided. A remote attacker can send a chunked request without the terminating zero-length chunk, causing uncontrolled memory allocation on the server. This leads to potential exhaustion of system memory and results in a server crash or unresponsiveness. Version 0.20.1 fixes the issue by enforcing limits during parsing. If the limit is exceeded at any point during reading, the connection is terminated immediately. A short-term workaround through a Reverse Proxy is available. If updating the library immediately is not feasible, deploy a reverse proxy (e.g., Nginx, HAProxy) in front of the `cpp-httplib` application. Configure the proxy to enforce maximum request body size limits, thereby stopping excessively large requests before they reach the vulnerable library code.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Cpp-httplib< 0.20.1

Remediation

Fixed in
Cpp-httplib≥ 0.20.1

References

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Frequently asked

Is CVE-2025-46728 being actively exploited?

CVE-2025-46728 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.66%.

How severe is CVE-2025-46728?

CVE-2025-46728 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.66% probability of exploitation.

Which products are affected by CVE-2025-46728?

Affected products include Cpp-httplib.

How do I fix CVE-2025-46728?

Upgrade affected software to a fixed version, for example Cpp-httplib 0.20.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-46728 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.