CVE-2026-74766
UnknownSummary
Net::IDN::Punycode versions from 2.301 before 2.590 for Perl allow a heap use-after-free via a decoded code point that reallocates the output buffer in decode_punycode. Decoding an attacker-supplied punycode label reads and writes freed heap memory.
Risk Assessment
An attacker can supply a crafted punycode label to cause memory corruption, application crash, or potentially arbitrary code execution.
Recommendation
Update Net::IDN::Punycode to version 2.590 or later. Avoid decoding untrusted punycode labels until patched.
Other vulnerabilities in Net::IDN::Punycode
See all- CVE-2026-87082Unknown
Net::IDN::Punycode versions before 2.590 for Perl do not validate UTF-8 input in encode_punycode. A flagged string with malformed bytes can hang, crash, or return a wrong label. Only direct calls to encode_punycode are affected; the decoder is not vulnerable.
- CVE-2026-87079Unknown
Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding long labels in decode_punycode. No label length limit exists in the to-Unicode direction, enabling CPU exhaustion attacks.
- CVE-2026-87078Unknown
Net::IDN::Punycode versions from 2.302 before 2.590 for Perl leak the output buffer on every rejected label in decode_punycode. No label length limit exists in the to-Unicode direction, allowing memory growth.
- CVE-2026-74765Unknown
Net::IDN::Punycode versions before 2.590 for Perl allow an out-of-bounds read via integer overflow of the delta accumulator in encode_punycode. Large code points can cause the digit index to leave the range of the digit table, leading to memory corruption or crash.
- CVE-2016-15059Unknown
Net::IDN::Punycode versions before 2.301 for Perl allow a heap buffer overflow via unchecked writes past the output buffer in encode_punycode. Some digit writes and the terminating NUL write do not check for room, leading to out-of-bounds writes.
Original NVD description (English source)
Net::IDN::Punycode versions from 2.301 before 2.590 for Perl allow a heap use-after-free via a decoded code point that reallocates the output buffer in decode_punycode. The XS backend inserts each decoded code point into the string buffer of the scalar it returns. decode_punycode computes the insertion pointer first and only then grows the buffer when the code point does not fit. The growth reallocates the buffer and updates every pointer except the insertion pointer, so the move that follows and the write of the code point go through a freed pointer. The buffer starts at twice the label length, and a code point above U+FFFF takes four bytes in the output, so a label of such code points outgrows it and forces the reallocation. Version 2.301, the fix for CVE-2016-15059, introduced the defect. Only the XS backend is affected. Decoding an attacker-supplied punycode label reads and writes freed heap memory.