CVE-2025-46728
cpp-httplib has Unbounded Memory Allocation in Chunked/No-Length Requests
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
7.5
cpp-httplib has Unbounded Memory Allocation in Chunked/No-Length Requests
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.
- Record
CVE-2025-46728- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
EUVDEUVD-2025-13496
7.5
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.
- Record
EUVD-2025-13496- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
NVD
7.5
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.
- Record
CVE-2025-46728- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
OSV
7.5
cpp-httplib has Unbounded Memory Allocation in Chunked/No-Length Requests
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.
- Record
CVE-2025-46728- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2025-46728
7.5
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.
- Record
DEBIAN-CVE-2025-46728- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVOESA-2025-1610
7.5
cpp-httplib security update
A C++11 single-file header-only cross platform HTTP/HTTPS library. It's extremely easy to setup. Just include httplib.h file in your code!
Security Fix(es):
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.(CVE-2025-46728)
- Record
OESA-2025-1610- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 5 moreShow less
OSVOESA-2025-1611
7.5
cpp-httplib security update
A C++11 single-file header-only cross platform HTTP/HTTPS library. It's extremely easy to setup. Just include httplib.h file in your code!
Security Fix(es):
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.(CVE-2025-46728)
- Record
OESA-2025-1611- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVOESA-2025-1612
7.5
cpp-httplib security update
A C++11 single-file header-only cross platform HTTP/HTTPS library. It's extremely easy to setup. Just include httplib.h file in your code!
Security Fix(es):
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.(CVE-2025-46728)
- Record
OESA-2025-1612- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVOESA-2025-1613
7.5
cpp-httplib security update
A C++11 single-file header-only cross platform HTTP/HTTPS library. It's extremely easy to setup. Just include httplib.h file in your code!
Security Fix(es):
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.(CVE-2025-46728)
- Record
OESA-2025-1613- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2025-46728
7.5
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.
- Record
UBUNTU-CVE-2025-46728- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVopenSUSE-SU-2025:15084-1 No score
cpp-httplib-devel-0.20.1-1.1 on GA media
These are all security issues fixed in the cpp-httplib-devel-0.20.1-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2025:15084-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
cpp-httplibDebian:12 |
All versions, plus listed versions 0.11.4+ds-10.11.4+ds-1+deb12u10.11.4+ds-20.11.4+ds-30.13.1+ds-1 Show 22 moreShow less0.14.0+ds-10.14.1+ds-10.14.1+ds-20.14.2+ds-10.14.3+ds-10.14.3+ds-1.10.14.3+ds-1.1~exp10.15.3+ds-10.15.3+ds-20.15.3+ds-30.16.0+ds-10.16.3+ds-10.16.3+ds-20.18.0+ds-10.18.7-10.20.1+ds-30.25.0+ds-10.26.0+ds-20.41.0+ds-10.41.0+ds-20.41.0+ds-30.41.0+ds-3~bpo13+1 |
None known |
cpp-httplibDebian:13 |
before 0.18.7-1+deb13u1, plus listed versions 0.18.7-1 |
0.18.7-1+deb13u1 |
cpp-httplibDebian:14 |
before 0.25.0+ds-3, plus listed versions 0.18.7-10.20.1+ds-30.25.0+ds-1 |
0.25.0+ds-3 |
cpp-httplibopenEuler:22.03-LTS-SP4 |
before 0.12.4-4.oe2203sp4 | 0.12.4-4.oe2203sp4 |
cpp-httplibopenEuler:24.03-LTS |
before 0.14.0-4.oe2403 | 0.14.0-4.oe2403 |
cpp-httplibopenEuler:24.03-LTS-SP1 |
before 0.14.0-4.oe2403sp1 | 0.14.0-4.oe2403sp1 |
cpp-httplibopenEuler:22.03-LTS-SP3 |
before 0.12.4-4.oe2203sp3 | 0.12.4-4.oe2203sp3 |
cpp-httplibUbuntu:Pro:22.04:LTS |
All versions, plus listed versions 0.9.9+ds-10.9.10+ds-10.10.1+ds-10.10.2+ds-10.10.3+ds-10.10.3+ds-1ubuntu0.1~esm10.10.3+ds-1ubuntu0.1~esm2 |
None known |
cpp-httplibUbuntu:Pro:24.04:LTS |
All versions, plus listed versions 0.13.1+ds-1ubuntu10.14.3+ds-10.14.3+ds-1.10.14.3+ds-1.1build10.14.3+ds-1.1build20.14.3+ds-1.1ubuntu0.1~esm10.14.3+ds-1.1ubuntu0.1~esm2 |
None known |
cpp-httplibUbuntu:25.10 |
All versions, plus listed versions 0.18.7-10.18.7-1ubuntu0.25.10.10.18.7-1ubuntu0.25.10.2 |
None known |
cpp-httplibUbuntu:Pro:26.04:LTS |
All versions, plus listed versions 0.18.7-10.26.0+ds-2ubuntu20.26.0+ds-2ubuntu30.26.0+ds-2ubuntu3+esm1 |
None known |
cpp-httplibopenSUSE:Tumbleweed |
before 0.20.1-1.1 | 0.20.1-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-46728 is a high vulnerability (CVSS 7.5) in Cpp-httplib Project Cpp-httplib, published May 6, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.68%, the 52nd percentile. Fixed in cpp-httplib 0.18.7-1+deb13u1.
References
github.com/yhirose/cpp-httplib/security/advisories/GHSA-px83-72rx-v57c
github.com/yhirose/cpp-httplib/commit/7b752106ac42bd5b907793950d9125a0972c8e8e
github.com/CVEProject/cvelistV5/tree/main/cves/2025/46xxx/CVE-2025-46728.json
nvd.nist.gov/vuln/detail/CVE-2025-46728
security-tracker.debian.org/tracker/CVE-2025-46728
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2025-1610
Show 6 moreShow less
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2025-1611
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2025-1612
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2025-1613
ubuntu.com/security/CVE-2025-46728
cve.org/CVERecord?id=CVE-2025-46728
suse.com/security/cve/CVE-2025-46728