8

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2025-26519

CVE-2025-26519: musl libc 0.9.13 through 1.2.5 before 1.2.6 has an out-of-bounds write vulnerability when an...

musl libc 0.9.13 through 1.2.5 before 1.2.6 has an out-of-bounds write vulnerability when an attacker can trigger iconv conversion of untrusted EUC-KR text to UTF-8.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2025-26519

CVE-2025-26519:

8

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

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Root Cause Analysis

The analysis of the provided commit patches (c47ad25ea3b484e10326f933e927c0bc8cded3da and e5adcd97b5196e29991b524237381a0202a60659) for musl libc indicates that the iconv function in src/locale/iconv.c is the locus of the vulnerability. The first commit (c47ad25ea3b484e10326f933e927c0bc8cded3da) hardens the UTF-8 output path by adding a check for the return value of wctomb_utf8. The commit message explicitly states that if wctomb_utf8 returns (size_t)-1 (due to an invalid Unicode Scalar Value from a decoder bug), the subsequent adjustments to the output buffer pointer and byte count would overflow, leading to an out-of-bounds write. This fix is applied directly within the iconv function. The second commit (e5adcd97b5196e29991b524237381a0202a60659) fixes an erroneous input validation in the EUC-KR decoder part of the iconv function. This incorrect validation could lead to out-of-bounds table reads and the generation of invalid wide characters. These invalid characters, when processed by wctomb_utf8 (called from iconv), would cause wctomb_utf8 to return (size_t)-1, triggering the out-of-bounds write mentioned in the first commit. Both patches modify code within the iconv function, addressing either the cause of invalid data generation (EUC-KR decoder bug) or the unsafe handling of errors arising from such data (mishandling wctomb_utf8's error return). Therefore, iconv is the function that contains the vulnerability and would appear in a runtime profile during exploitation.

Vulnerable functions

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WAF Rule

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Reasoning

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