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...
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Basic Information
Technical Details
Vulnerability Intelligence
Miggo AI
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.