GHSA-34xg-wgjx-8xph · Severity: medium · Ecosystem: composer — guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation
guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Versions prior to 2.10.2 contain improper Host header validation when parsing raw HTTP request messages and when deriving a server request URI from server variables. An attacker can provide a malformed Host header containing URI authority delimiters, such as `[email protected]`. When the Host value is used to construct a URI, the malformed value can be reinterpreted as URI userinfo and host. This can cause the PSR-7 request URI host to differ from the original Host header value. Applications are affected if they parse attacker-controlled raw HTTP requests with `GuzzleHttp\Psr7\Message::parseRequest()` or the legacy 1.x `GuzzleHttp\Psr7\parse_request()` function, or if they build server requests from attacker-controlled server variables, then rely on the resulting URI host for routing, allow-list checks, or forwarding decisions. In affected forwarding or gateway scenarios, this may cause requests or credentials to be sent to an unintended host. The issue is patched in `2.10.2`. `1.x` is end-of-life and will not receive a patch. Some workarounds are available. Validate the `Host` header as `uri-host [ ":" port ]` before calling `Message::parseRequest()` or legacy `parse_request()` on untrusted HTTP request data, or before deriving routing and forwarding decisions from a parsed request URI. Reject Host values containing userinfo, path, query, or fragment delimiters.
Conclusion & alert: CVE-2026-48998 is rated Low Risk (29.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.31%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.04% | 0.31% | +0.27% |
| 2 | 2026-06-12 | — | 0.04% | — |
Full EPSS history (2 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 5.3 | 3.1 | MEDIUM |
|
3.9 | 1.4 | [email protected] |
GHSA-34xg-wgjx-8xph · Severity: medium · Ecosystem: composer — guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
not yet assigned | CVE-2026-48998 not yet assigned priority: Debian including 1 source packages (php-guzzlehttp-psr7), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. | https://security-tracker.debian.org/tracker/CVE-2026-48998 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2026-48998 |
ubuntu
|
medium | CVE-2026-48998 medium priority: Ubuntu including 1 source packages (php-guzzlehttp-psr7), 6 status rows across 6 suites (focal, jammy, noble, questing, resolute, upstream): needs-triage 6. | https://ubuntu.com/security/CVE-2026-48998 |
| URL | Tags |
|---|---|
| https://github.com/guzzle/psr7/security/advisories/GHSA-34xg-wgjx-8xph | Mitigation Vendor Advisory |