CVE-2026-33745
cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
- Record
CVE-2026-33745- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
EUVDEUVD-2026-16515
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
- Record
EUVD-2026-16515- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
NVD
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
- Record
CVE-2026-33745- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
OSV
cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
- Record
CVE-2026-33745- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-200
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-33745
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
- Record
DEBIAN-CVE-2026-33745- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
OSVOESA-2026-1867
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++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.(CVE-2026-33745)
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.(CVE-2026-34441)
- Record
OESA-2026-1867- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
Show 5 moreShow less
OSVOESA-2026-1868
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++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.(CVE-2026-33745)
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.(CVE-2026-34441)
- Record
OESA-2026-1868- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
OSVOESA-2026-1869
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++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.(CVE-2026-33745)
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.(CVE-2026-34441)
- Record
OESA-2026-1869- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
OSVOESA-2026-1870
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++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.(CVE-2026-33745)
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.(CVE-2026-34441)
- Record
OESA-2026-1870- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-33745
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
- Record
UBUNTU-CVE-2026-33745- CVSS 3.1
- 7.4 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
OSVopenSUSE-SU-2026:10573-1 No score
cpp-httplib-devel-0.42.0-1.1 on GA media
These are all security issues fixed in the cpp-httplib-devel-0.42.0-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:10573-1- 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 |
All versions, plus listed versions 0.18.7-10.18.7-1+deb13u10.20.1+ds-30.25.0+ds-10.26.0+ds-2 Show 4 moreShow less0.41.0+ds-10.41.0+ds-20.41.0+ds-30.41.0+ds-3~bpo13+1 |
None known |
cpp-httplibDebian:14 |
before 0.41.0+ds-3, plus listed versions 0.18.7-10.20.1+ds-30.25.0+ds-10.26.0+ds-20.41.0+ds-10.41.0+ds-20.41.0+ds-3~bpo13+1 |
0.41.0+ds-3 |
cpp-httplibopenEuler:24.03-LTS From an advisory covering 2 CVEs |
before 0.40.0-1.oe2403 | 0.40.0-1.oe2403 |
cpp-httplibopenEuler:24.03-LTS-SP1 From an advisory covering 2 CVEs |
before 0.40.0-1.oe2403sp1 | 0.40.0-1.oe2403sp1 |
cpp-httplibopenEuler:24.03-LTS-SP2 From an advisory covering 2 CVEs |
before 0.40.0-1.oe2403sp2 | 0.40.0-1.oe2403sp2 |
cpp-httplibopenEuler:24.03-LTS-SP3 From an advisory covering 2 CVEs |
before 0.40.0-1.oe2403sp3 | 0.40.0-1.oe2403sp3 |
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:26.10 |
All versions, plus listed versions 0.26.0+ds-2ubuntu30.26.0+ds-2ubuntu4 |
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 From an advisory covering 2 CVEs |
before 0.42.0-1.1 | 0.42.0-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-33745 is a high vulnerability (CVSS 7.4) in Yhirose Cpp-httplib, published March 27, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.27%, the 18th percentile. Fixed in cpp-httplib 0.41.0+ds-3.
References
github.com/yhirose/cpp-httplib/security/advisories/GHSA-6hrp-7fq9-3qv2
nvd.nist.gov/vuln/detail/CVE-2026-33745
security-tracker.debian.org/tracker/CVE-2026-33745
openeuler.org/zh/security/security-bulletins/detail?id=openEuler-SA-2026-1867
Show 7 moreShow less
ubuntu.com/security/CVE-2026-33745
cve.org/CVERecord?id=CVE-2026-33745
suse.com/security/cve/CVE-2026-33745