CVE-2026-49214CWE-113CWE-20CWE-93

guzzlehttp/psr7 has CRLF Injection via URI Host Component

Medium · published June 11, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
22.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00310 · 22.6th percentile
Weaknesses
CWE-113 · Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting'); CWE-20 · Improper Input Validation; CWE-93 · Improper Neutralization of CRLF Sequences ('CRLF Injection')
Published
2026-06-11T12:38Z
EPSS history
Timeline
  • 11 JUN 12:38Z
    guzzlehttp/psr7 has CRLF Injection via URI Host Component
    cvelistv5