CVE-2026-92842

Received Received - Intake

PHP Stream Filters Heap Out-of-Bounds Read via Line Break Truncation

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: PHP Group

Description

The convert.base64-encode, convert.quoted-printable-encode and convert.quoted-printable-decode stream filters accept a line-break-chars option whose length is tracked separately from the string itself. The filter constructors duplicate the value with pestrdup(), which stops at the first NUL byte, while keeping the original length. When the filter later emits a line break it copies the recorded length out of the truncated allocation, reading past its end and placing adjacent heap bytes into the filter output.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-25

Last Modified

2026-09-25

Generated

2026-09-26

AI Q&A

2026-09-26

EPSS Evaluated

N/A

NVD

CVE-2026-92842

Affected Vendors & Products

Vendor	Product	Version / Range
php	php	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-125	The product reads data past the end, or before the beginning, of the intended buffer.
CWE-122	A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Attack-Flow Graph

Executive Summary

This vulnerability involves PHP stream filters used for base64 and quoted-printable encoding/decoding. The filters accept a line-break-chars option where the length is tracked separately from the string. The constructor duplicates the value but stops at the first NUL byte, while the original length is retained. Later, when emitting line breaks, the filter copies the recorded length from the truncated allocation, causing it to read past the end of the allocated memory and include adjacent heap bytes in the output.

Detection Guidance

This vulnerability is specific to PHP's stream filters and cannot be directly detected via standard network or system commands. It requires inspecting PHP applications using the affected stream filters (base64-encode, quoted-printable-encode, quoted-printable-decode) with the line-break-chars option. Check PHP logs for crashes or memory corruption when these filters are used.

Impact Analysis

This vulnerability could allow an attacker to read sensitive data from adjacent memory locations. If exploited, it may lead to information disclosure, potentially exposing confidential or sensitive information processed by the affected PHP application.

Compliance Impact

This vulnerability could lead to unauthorized data exposure, violating GDPR's data protection principles or HIPAA's security requirements for protected health information. Organizations using affected PHP versions may face compliance violations, legal penalties, and reputational damage if exploited.

Mitigation Strategies

Update PHP to the latest patched version as soon as possible to address the stream filter vulnerability. Monitor vendor advisories for specific version details.

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