Socket versions before 2.041 for Perl have an out-of-bounds heap read.
In Socket.xs, pack_ip_mreq_source() checks the length of its source argument before the argument is read, so the check tests the byte length carried over from the preceding multiaddr argument instead. Both addresses occupy a 4-byte field, so a valid multiaddr lets a source of any length pass the check, and the source is then copied into the 4-byte imr_sourceaddr field with a fixed-size copy. A source shorter than 4 bytes is not rejected, and the copy reads up to 3 bytes past the end of its buffer.
Calling pack_ip_mreq_source() with a source value shorter than 4 bytes copies adjacent heap memory into the returned packed structure.
{
"cna_assigner": "CPANSec",
"cwe_ids": [
"CWE-125",
"CWE-805"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12087.json",
"unresolved_ranges": [
{
"extracted_events": [
{
"fixed": "2.041"
}
],
"source": "AFFECTED_FIELD"
},
{
"extracted_events": [
{
"fixed": "2.041"
}
],
"source": "DESCRIPTION"
}
]
}