CVE-2026-59882Network attack vector

Security-control bypass via malformed URI host validation

Published Jul 8, 2026 · Updated Jul 8, 2026

Host interpretation conflict in Guzzle PSR-7 before 2.12.3 allows remote attackers to influence security or routing decisions via malformed URIs. Uri::assertValidHost() checks only control characters, accepting authority delimiters, embedded ports, and malformed IPv6 brackets that make Uri::getHost() disagree with the on-wire authority. Exploitation requires an application to accept attacker-controlled host data and then trust Uri::getHost(); consequences include SSRF, access-control bypass, cookie-scope errors, and unintended routing.

CVSS severity4.2
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Host interpretation conflict in Guzzle PSR-7 before 2.12.3 allows remote attackers to influence security or routing decisions via malformed URIs. Uri::assertValidHost() checks only control characters, accepting authority delimiters, embedded ports, and malformed IPv6 brackets that make Uri::getHost() disagree with the on-wire authority. Exploitation requires an application to accept attacker-controlled host data and then trust Uri::getHost(); consequences include SSRF, access-control bypass, cookie-scope errors, and unintended routing.

The record

CVE
CVE-2026-59882
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
Guzzle
Product
Guzzle PSR-7
Classifications
CWE-436
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.12.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Guzzle · Guzzle PSR-7version=< 2.12.3

Published CVSS scores

4.2GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-436Interpretation Conflict

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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