CVE-2026-49214
mediumpriority · track · 0EPSS 0.002 · 9 %ileEUUSEPSS · scored 2026-10-27
guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Versions prior to 2.10.2 did not reject ASCII control characters, whitespace, or DEL in first-party URI host components. A vulnerable flow is: First, an application accepts a user-controlled URL. Second, the URL is used to construct a PSR-7 `Uri` or `Request`. Third, the host component contains CRLF or another header-unsafe character. Fourth, the host is copied into the PSR-7 `Host` header when no explicit `Host` header is provided. Finally, the request is serialized or sent by an HTTP client that does not independently reject the malformed host. In that flow, an attacker can cause the serialized request to contain additional attacker-controlled header lines. For example, a host containing `"\r\nX-Injected: yes"` can cause the generated `Host` header to span multiple HTTP header lines. Applications are affected when they use user-controlled URLs for outbound HTTP requests, URL forwarding, proxying, crawling, webhook delivery, or similar request-dispatch flows. In deployments involving HTTP/1.1 connection reuse, proxies, gateways, or load balancers, this malformed request may also contribute to request smuggling or cache poisoning, depending on how downstream components parse the request. The issue is patched in `2.10.2` and later. `1.x` is end-of-life and will not receive a patch. As a workaround, validate and reject all untrusted URI strings before constructing PSR-7 `Uri` or `Request` instances. Reject input containing ASCII control characters, whitespace, or DEL, including CRLF, tab, space, NUL, or DEL characters. Applications that forward requests should also ensure the final HTTP client or serializer rejects invalid URI and header data before writing requests to the network.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-hq7v-mx3g-29hwguzzlehttp/psr7 has CRLF Injection via URI Host Component2026-06-11ghsa · osvUS
## Impact `guzzlehttp/psr7` did not reject ASCII control characters, whitespace, or DEL in first-party URI host components. The issue requires a PSR-7 request to be serialized into a raw HTTP/1.x message, for example with `GuzzleHttp\Psr7\Message::toString()` or an equivalent custom serializer. Creating a `Uri`, `Request`, or other PSR-7 object alone is not sufficient. The malformed host must be copied into the serialized `Host` header without further validation. A vulnerable flow is: 1. An application accepts a user-controlled URL. 2. The URL is used to construct a PSR-7 `Uri` or `Request`. 3. The host component contains CRLF or another header-unsafe character. 4. The request is serialized into a raw HTTP/1.x message without an explicit `Host` header. 5. The host is copied into the serialized `Host` header. 6. The serialized request is written to the network or otherwise processed by software that does not independently reject the malformed host. In that flow, an attacker can cause the serialized request to contain additional attacker-controlled header lines. For example, a host containing `"\r\nX-Injected: yes"` can cause the generated `Host` header to span multiple HTTP header lines. This is not the normal request-sending path used by `guzzlehttp/guzzle`. Applications using `guzzlehttp/psr7` only through Guzzle's standard HTTP client APIs are not expected to be affected. Applications are most likely to be affected when they manually serialize PSR-7 requests, forward raw HTTP messages, or use custom transports, proxying, crawling, webhook delivery, or similar request-dispatch code that serializes requests without independently validating URI hosts and header data. In deployments involving HTTP/1.1 connection reuse, proxies, gateways, or load balancers, this malformed serialized request may also contribute to request smuggling or cache poisoning, depending on how downstream components parse the request. ## Patches The issue is patched in `2.10.2` and later. `1.x` is end-of-life and will not receive a patch. ## Workarounds If you cannot upgrade immediately, validate and reject all untrusted URI strings before constructing PSR-7 `Uri` or `Request` instances. Reject input containing ASCII control characters, whitespace, or DEL, including CRLF, tab, space, NUL, or DEL characters: ```php if (preg_match('/[\x00-\x20\x7F]/', $untrustedUrl)) { throw new \InvalidArgumentException('Insecure URL detected'); } ``` Applications that manually serialize or forward requests should also ensure the final HTTP client, transport, or serializer rejects invalid URI and header data before writing requests to the network. ## References * https://www.rfc-editor.org/rfc/rfc9112.html#section-3.2 * https://www.rfc-editor.org/rfc/rfc9112.html#section-5 * https://www.rfc-editor.org/rfc/rfc9112.html#section-11.2 * https://www.rfc-editor.org/rfc/rfc9110.html#section-7.2
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (4)
External citations — patches, advisories, analysis.
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan