CVE-2026-6104
📛 CVE Title
Global buffer over-read in mb_convert_encoding() with attacker-supplied encoding
Description
In PHP versions 8.4.* before 8.4.21 and 8.5.* before 8.5.6, when an encoding name containing an embedded NUL byte is passed to mb_convert_encoding() or related mbstring functions, the code incorrectly assumes that when strncasecmp() returns 0 it means the strings have the same length. This can lead to out-of-bounds read of global memory, potentially causing a crash or information disclosure or crash. Affected functions include mb_convert_encoding(), mb_detect_encoding(), mb_convert_variables(), and mb_detect_order(), as well as the mbstring.detect_order and mbstring.http_output INI settings.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- php
- CVSS severity
- MEDIUM
- CVSS score
- 6.3 / 10
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:L/SI:N/SA:L/RE:M/U:Amber- Effective score
- 6.3 / 10 MEDIUM source: CNA overview
- CWE(s)
-
CWE-125 - Reserved
- 2026-04-11
- Published
- 2026-05-10 06:35 UTC
- Last updated
- 2026-05-11 15:04 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/6xxx/CVE-2026-6104.json
- Linked Threat
- CVE-2026-6104 — CVE-2026-6104
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-05-10 06:16:07 UTC
- NVD last modified
- 2026-05-12 17:35:59 UTC
- NVD CVSS v3.1
- 9.1 / 10 CRITICAL source: nvd@nist.gov
- NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H- Exploitability subscore
- 3.9 / 10
- Impact subscore
- 5.2 / 10
- EPSS score
- 0.0002 (probability of exploitation in next 30 days)
- EPSS percentile
- 6.19% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24
NVD / KEV / EPSS data refreshed 2026-05-25 07:19 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-28979 - Assigner
- php
- Published
- May 10, 2026, 4:35:17 AM
- Updated
- May 11, 2026, 1:04:58 PM
- EUVD base score (CVSS 4.0)
-
6.3 / 10
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:L/SI:N/SA:L/RE:M/U:Amber - EUVD-reported EPSS
- 0.0200
- Vendors
- PHP Group
- Products
-
PHP (8.5.* <8.5.6)PHP (8.4.* <8.4.21)
ENISA description: In PHP versions 8.4.* before 8.4.21 and 8.5.* before 8.5.6, when an encoding name containing an embedded NUL byte is passed to mb_convert_encoding() or related mbstring functions, the code incorrectly assumes that when strncasecmp() returns 0 it means the strings have the same length. This can lead to out-of-bounds read of global memory, potentially causing a crash or information disclosure or crash. Affected functions include mb_convert_encoding(), mb_detect_encoding(), mb_convert_variables(), and mb_detect_order(), as well as the mbstring.detect_order and mbstring.http_output INI settings.
EUVD references (1)
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| PHP Group | PHP |
8.4.* (affected),
8.5.* (affected)
|
— |
Affected products — CPE 2.3 (1) NVD
NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
Vendor references (1)
References embedded in the original CVE record by the assigning CNA.
MITRE references (1) cveawg.mitre.org
Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.
Web references (7)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
- https://attackerkb.com/topics/CVE-2026-6104 rapid7:attackerkb.com
- https://security.alpinelinux.org/vuln/CVE-2026-6104 rapid7:security.alpinelinux.org
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-28979 rapid7:euvd.enisa.europa.eu
- http://cwe.mitre.org/data/definitions/125.html rapid7:cwe.mitre.org
- https://www.first.org/epss/ tenable:www.first.org
- https://nvd.nist.gov/vuln/detail/CVE-2026-6104 tenable:nvd.nist.gov
- https://www.cve.org/CVERecord?id=CVE-2026-6104 tenable:www.cve.org
NVD-tagged references (1)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53 security@php.net Vendor Advisory
Remediations (17)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:blog.qualys.com
With Qualys Policy Audit's out-of-the-box mitigation or Compensatory Controls, which reduce the risk of a vulnerability being exploited because the remediation ( fix / patch ) cannot be done immediately, these security controls are not recommended by any industry standards, such as CIS and DISA-STIG.
2026-05-23 21:03 UTC -
web:blog.talosintelligence.com
Microsoft has released its monthly security update for May 2026 , which includes 137 vulnerabilities affecting a range of products, including 16 that Microsoft marked as "critical".
2026-05-23 21:03 UTC -
web:cyberpress.org
Microsoft's February 2026 Patch Tuesday dropped with major urgency, fixing 54 security flaws across Windows, Office, Exchange, Azure, and more. The standout issue? Six zero-day vulnerabilities are already under active attack in the wild. These are bugs hackers exploited before Microsoft could patch them. IT teams must apply these updates now to avoid breaches. Zero-days let attackers slip ...
2026-05-23 21:03 UTC -
web:cyberscoop.com
Threats Microsoft addresses 137 vulnerabilities in May's Patch Tuesday, including 13 rated critical The high volume of vulnerabilities reflects a growing trend researchers have been anticipating as artificial intelligence models are deployed to find previously uncovered defects in code.
2026-05-23 21:03 UTC -
web:cybersecuritynews.com
Microsoft has released its April 2026 Patch Tuesday security update, addressing 168 vulnerabilities across its product portfolio including one actively exploited zero-day and one publicly disclosed flaw that organizations must prioritize immediately.
2026-05-23 21:03 UTC -
web:nvd.nist.gov
An official website of the United States government Here's how you know
2026-05-23 21:03 UTC -
web:portal.msrc.microsoft.com
The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.
2026-05-23 21:03 UTC -
web:www.bleepingcomputer.com
Today is Microsoft's May 2026 Patch Tuesday, with security updates for 120 flaws and no zero-days disclosed this month.
2026-05-23 21:03 UTC -
web:www.oracle.com
This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.
2026-05-23 21:03 UTC -
web:www.thehackerwire.com
Frequently Asked Questions What is CVE-2026-6104 ? How severe is CVE-2026-6104 ? What Php products are affected by CVE-2026-6104 ? How do I fix or mitigate CVE-2026-6104 ? When was CVE-2026-6104 disclosed?
2026-05-23 21:03 UTC -
web:blog.qualys.com
Microsoft has rolled out its March 2026 Patch Tuesday updates, delivering a fresh batch of security fixes designed to keep Windows environments protected from emerging threats.
2026-05-26 02:50 UTC -
web:cybersecuritynews.com
Microsoft released its March 2026 Patch Tuesday security update on March 10, 2026 , addressing 78 vulnerabilities across Windows, Microsoft Office, Azure, SQL Server, and .NET. The update includes one actively exploited zero-day vulnerability and multiple Critical-rated flaws demanding immediate attention from security teams. The most urgent fix this month is CVE - 2026 -21262, the sole zero-day ...
2026-05-26 02:50 UTC -
web:krebsonsecurity.com
Microsoft Corp. today pushed security updates to fix at least 77 vulnerabilities in its Windows operating systems and other software.
2026-05-26 02:50 UTC -
web:www.lansweeper.com
Patch Tuesday Microsoft report by Lansweeper. get an overview from all the Microsoft Patch Tuesday 's and fix the vulnerabilities.
2026-05-26 02:50 UTC -
web:www.rapid7.com
Microsoft is publishing 77 vulnerabilities this Patch Tuesday, including two publicly disclosed zero-day vulnerabilities.
2026-05-26 02:50 UTC -
web:www.techrepublic.com
Microsoft's March Patch Tuesday fixes 78 vulnerabilities, including Office preview pane flaws, an Excel Copilot data leak risk, and an AI-discovered 9.8 severity bug.
2026-05-26 02:50 UTC -
web:www.windowslatest.com
Windows 11 March 2026 Patch Tuesday update adds Emoji 16.0, Sysmon, network speed test, reliability improvements, and security fixes.
2026-05-26 02:50 UTC
AI Forensic Analysis
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-6104.json.
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