CVE-2025-53628 cpp-httplib does not limit the length of a line
An attacker can cause arbitrary memory allocation and denial of service in cpp-httplib by sending excessively long lines.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-53628?
CVE-2025-53628 is a medium-severity denial of service vulnerability in yhirose cpp-httplib, published on 10 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.20.1, cpp-httplib does not have a limit for a unique line, permitting an attacker to explore this to allocate memory arbitrarily. This vulnerability is fixed in 0.20.1. NOTE: This vulnerability is related to CVE-2025-53629.
Which versions are affected by CVE-2025-53628?
It affects 1 product.
Products include Yhirose Cpp-Httplib.
How do I fix CVE-2025-53628?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-53628 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-53628 exists.
Other vulnerabilities in yhirose cpp-httplib
- CVE-2025-66570 cpp-httplib Untrusted HTTP Header Handling: Internal Header Shadowing (REMOTE*/LOCAL*)
- CVE-2026-45372 cpp-httplib: HTTP header value percent-decoding in server-side `parse_header` enables CRLF injection
- CVE-2026-46527 Null dereference in cpp-httplib
- CVE-2026-32627 cpp-httplib has a Silent TLS Certificate Verification Bypass on HTTPS Redirect via Proxy
- CVE-2026-22776 cpp-httplib vulnerable to a denial of service (DOS) using a zip bomb
Sources
Also known as DEBIAN-CVE-2025-53628, ECHO-afa3-f31f-8c19, UBUNTU-CVE-2025-53628.