CVE-2026-75922
Reverse::Proxy versions before 0.04 for Perl allow HTTP request smuggling via a percent-decoded PATH_INFO written unencoded to the upstream request line
Description
Reverse::Proxy versions before 0.04 for Perl allow HTTP request smuggling via a percent-decoded PATH_INFO written unencoded to the upstream request line. PSGI hands PATH_INFO to an application percent-decoded, so a %XX sequence in the client URL has become a raw byte by the time the proxy sees it. The proxy appends that byte string to the upstream base URL, and for an Upgrade tunnel writes it into a request line it serializes itself, re-encoding nothing in either path. The HTTP client that sends the resulting URL does not validate the target either. A path containing %0d%0a therefore arrives at the upstream as a CRLF that ends the request line, and a decoded space, '?' or '#' truncates it the same way. Everything the client writes after the CRLF is read by the upstream as a second request. On the buffered path it arrives on a keep-alive connection the proxy pools and reuses for other clients. Its method, path and headers are all chosen by the client, and the upstream attributes it to the proxy, so it reaches upstream paths that the proxy's own routing does not expose.
INFO
Published Date :
Aug. 23, 2026, 7:16 p.m.
Last Modified :
Oct. 14, 2026, 1:10 p.m.
Remotely Exploit :
Yes !
Source :
9b29abf9-4ab0-4765-b253-1875cd9b441e
Affected Products
The following products are affected by CVE-2026-75922
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update the Reverse::Proxy Perl module to version 0.04 or later.
- Avoid using percent-decoded characters in PATH_INFO.
- Validate URLs received from clients.
- Sanitize upstream request lines.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-75922.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-75922 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-75922
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-75922 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-75922 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 14, 2026
Action Type Old Value New Value Added Translation Title: Reverse::Proxy versions before 0.04 for Perl allow HTTP request smuggling via a percent-decoded PATH_INFO written unencoded to the upstream request line, Description: Las versiones de Reverse::Proxy anteriores a la 0.04 para Perl permiten el contrabando de solicitudes HTTP a través de un PATH_INFO decodificado por porcentaje, escrito sin codificar en la línea de solicitud ascendente. PSGI entrega PATH_INFO a una aplicación decodificado por porcentaje, por lo que una secuencia %XX en la URL del cliente se ha convertido en un byte sin procesar para cuando el proxy la ve. El proxy añade esa cadena de bytes a la URL base ascendente, y para un túnel de actualización lo escribe en una línea de solicitud que serializa él mismo, sin recodificar nada en ninguna de las rutas. El cliente HTTP que envía la URL resultante tampoco valida el objetivo. Una ruta que contiene %0d%0a, por lo tanto, llega al ascendente como un CRLF que termina la línea de solicitud, y un espacio decodificado, '?' o '#' lo trunca de la misma manera. Todo lo que el cliente escribe después del CRLF es leído por el ascendente como una segunda solicitud. En la ruta almacenada en búfer, llega en una conexión keep-alive que el proxy agrupa y reutiliza para otros clientes. Su método, ruta y encabezados son todos elegidos por el cliente, y el ascendente lo atribuye al proxy, por lo que alcanza rutas ascendentes que el propio enrutamiento del proxy no expone. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 25, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Added SSVC {'id': 'CVE-2026-75922', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-25T19:30:17.806527Z'} -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Aug. 23, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/08/23/2 -
New CVE Received by 9b29abf9-4ab0-4765-b253-1875cd9b441e
Aug. 23, 2026
Action Type Old Value New Value Added Affected [{'modules': ['Reverse::Proxy'], 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '0.04', 'versionType': 'custom'}], 'packageURL': 'pkg:cpan/Reverse-Proxy', 'packageName': 'Reverse-Proxy', 'programFiles': ['Proxy.xs'], 'collectionURL': 'https://cpan.org/modules', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'rp_target_url'}, {'name': 'rp_raw_request'}]}] Added Description Reverse::Proxy versions before 0.04 for Perl allow HTTP request smuggling via a percent-decoded PATH_INFO written unencoded to the upstream request line. PSGI hands PATH_INFO to an application percent-decoded, so a %XX sequence in the client URL has become a raw byte by the time the proxy sees it. The proxy appends that byte string to the upstream base URL, and for an Upgrade tunnel writes it into a request line it serializes itself, re-encoding nothing in either path. The HTTP client that sends the resulting URL does not validate the target either. A path containing %0d%0a therefore arrives at the upstream as a CRLF that ends the request line, and a decoded space, '?' or '#' truncates it the same way. Everything the client writes after the CRLF is read by the upstream as a second request. On the buffered path it arrives on a keep-alive connection the proxy pools and reuses for other clients. Its method, path and headers are all chosen by the client, and the upstream attributes it to the proxy, so it reaches upstream paths that the proxy's own routing does not expose. Added CWE CWE-93 Added CWE CWE-444 Added Reference https://metacpan.org/release/LNATION/Reverse-Proxy-0.03/source/Proxy.xs#L386-399 Added Reference https://metacpan.org/release/LNATION/Reverse-Proxy-0.03/source/Proxy.xs#L654-666 Added Reference https://metacpan.org/release/LNATION/Reverse-Proxy-0.04/changes Added Reference https://metacpan.org/release/LNATION/Reverse-Proxy-0.04/source/Proxy.xs#L400-426