CVE-2026-59882

guzzlehttp/psr7: Host Confusion via Weak URI Host Validation

MEDIUM
6.5
CVSS Score
Published: July 8, 2026 at 03:50 PM UTC
Updated: October 25, 2026 at 05:10 PM UTC
2 products affected across 2 vendorsPsr 7PSR7

Using psr7 by guzzle?

Get instant alerts when new vulnerabilities affect psr7 - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM6.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Prior to 2.12.3, Uri::assertValidHost() does not reject URI host components containing authority delimiters, embedded ports, or malformed IPv6 brackets, allowing Uri::getHost() to disagree with the URI authority used for security or routing decisions. This issue is fixed in version 2.12.3.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.12.3
Affected range stops below 2.12.3, so it looks safe — our inference, not a vendor statement
90%
v < 2.12.3
Affected range stops below 2.12.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

x_refsource_CONFIRMMitigationVendor Advisory
Source: cverecord
https://github.com/guzzle/psr7/security/advisories/GHSA-c2w2-prh8-qm98
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/guzzle/psr7/pull/811
x_refsource_MISCProductRelease Notes
Source: cverecord
https://github.com/guzzle/psr7/releases/tag/2.12.3

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-436

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card