CVE-2026-6104 Details
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.
View at NVD
Exploit prediction scoring system (EPSS) score for CVE-2026-6104
EPSS (Exploit Prediction Scoring System): EPSS predicts the likelihood that a vulnerability will be exploited in the wild. A higher percentage means a greater chance of an exploit occurring. The EPSS model produces a probability score between 0 and 1 (0 and 100%).
0.03 Probability of exploitation activity being observed over the next 30 days (8th percentile)
CVSS score for CVE-2026-6104
CVSS (Common Vulnerability Scoring System): An open framework owned and managed by FIRST.Org, Inc. that assigns a numerical score from 0 to 10 to software vulnerabilities to indicate their severity.
9.1 Critical
Products affected by CVE-2026-6104
php 8.4.0
php 8.4.1
php 8.4.2
php 8.5.0
php 8.4.3
DVE Score by Bitsight AI
DVE scores complement traditional static scoring systems like CVSS with Bitsight AI powered real-time threat intelligence and underground cyber criminal activity so that security teams can reduce alert fatigue and focus on vulnerabilities most likely to be exploited.
Low
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CVE-2026-6104 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 65,365 36.63%
DE 17,671 9.90%
RU 14,217 7.97%
FR 12,681 7.11%
NL 9,378 5.25%
GB 7,468 4.18%
IT 6,726 3.77%
JP 5,540 3.10%
SE 3,496 1.96%
SG 2,905 1.63%

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CVE-2026-6104 Industry Footprint

Top 10 Identified Industries

*Service provider organizations (typically Technology and Telecommunications) are disproportionally represented in the results given their upstream ownership of end-user infrastructure. See our FAQs.

Industry* Observations Percentage
Technology 155,577 91.60%
Telecommunications 10,259 6.04%
Education 1,518 0.89%
Government/Politics 547 0.32%
Business Services 524 0.31%
Finance 180 0.11%
Utilities 163 0.10%
Manufacturing 147 0.09%
Consumer Goods 122 0.07%
Engineering 107 0.06%

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