guard XSSFBUtils wide-string byte length against int overflow#1079
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jmestwa-coder wants to merge 1 commit into
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guard XSSFBUtils wide-string byte length against int overflow#1079jmestwa-coder wants to merge 1 commit into
jmestwa-coder wants to merge 1 commit into
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pjfanning
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May 25, 2026
| sb.append(new String(data, offset, numBytes, StandardCharsets.UTF_16LE)); | ||
| numBytes+=4; | ||
| return numBytes; | ||
| sb.append(new String(data, offset, (int)numBytes, StandardCharsets.UTF_16LE)); |
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you should validate before the cast in the sb.append params
pjfanning
reviewed
May 25, 2026
| sb.append(new String(data, offset, numBytes, StandardCharsets.UTF_16LE)); | ||
| numBytes+=4; | ||
| return numBytes; | ||
| sb.append(new String(data, offset, (int)numBytes, StandardCharsets.UTF_16LE)); |
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you should validate before the cast in the sb.append params
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readXLWideString and readXLNullableWideString size the string as 2*(int)numChars, which overflows for char counts at or above 0x40000000 read from an .xlsb stream. The wrapped negative length slips past the offset+numBytes > data.length check, so an oversized record throws a raw StringIndexOutOfBoundsException instead of XSSFBParseException, and high-bit counts read the wrong length and desync the record stream. Compute the byte count in long so the bounds check applies before narrowing.