CVE-2026-91768Public exploitHinoki check available

FastCGI access bypass via truncated IPv6 comparison

Published Sep 25, 2026 · Updated Sep 25, 2026

Access control bypass in affected PHP-FPM 8.2–8.5 releases allows remote attackers to reach FastCGI over IPv6 TCP. The fcgi_is_allowed() IPv6 branch compares only 12 of 16 address bytes, expanding each listen.allowed_clients entry into a /96 prefix. Exploitation requires IPv6 TCP reachability and a source address sharing the allowed client's first 96 bits; Unix sockets and IPv4-only deployments are unaffected.

CVSS severity6.5
Medium
EPSS probability0.56%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Access control bypass in affected PHP-FPM 8.2–8.5 releases allows remote attackers to reach FastCGI over IPv6 TCP. The fcgi_is_allowed() IPv6 branch compares only 12 of 16 address bytes, expanding each listen.allowed_clients entry into a /96 prefix. Exploitation requires IPv6 TCP reachability and a source address sharing the allowed client's first 96 bits; Unix sockets and IPv4-only deployments are unaffected.

The record

CVE
CVE-2026-91768
Published
Sep 25, 2026
Updated
Sep 25, 2026
Vendor
PHP Development Team
Product
PHP
Classifications
T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=8.2.* <8.2.34
  2. Affected versionversion=8.3.* <8.3.35
  3. Affected versionversion=8.4.* <8.4.26
  4. Affected versionversion=8.5.* <8.5.11

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

PHP Development Team · PHPversion=8.2.* <8.2.34; version=8.3.* <8.3.35; version=8.4.* <8.4.26; version=8.5.* <8.5.11

Published CVSS scores

6.5GitHub Security AdvisoryCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1210Exploitation of Remote Services

Public exploit references

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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