CVE-2026-7383
Issue summary: A signed integer overflow when sizing the destination buffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap buffer overflow. Impact summary: A heap buffer overflow may lead to a crash or possibly attacker controlled code execution or other undefined behaviour. In ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination size for Unicode output is computed in a signed int: by left shift of the input character count for BMPSTRING (UTF-16) and UNIVERSALSTRING (UTF-32), and by summing per-character byte counts for UTF8STRING. The calculation overflows when the input reaches around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30 characters) the size wraps to zero, OPENSSL_malloc(1) is called, and the subsequent character copy writes several gigabytes past the one-byte allocation. X.509 certificate processing routes through ASN1_STRING_set_by_NID(), whose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID size limits cap the input length; no network protocol or certificate-handling path in OpenSSL exercises the overflow. Triggering the bug requires an application that calls ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly,
Schwachstellenklasse
Issue summary: A signed integer overflow when sizing the destination buffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap buffer overflow. Impact summary: A heap buffer overflow may lead to a crash or possibly attacker controlled code execution or other undefined behaviour. In ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination size for Unicode output is computed in a signed int: by left shift of the input character count for BMPSTRING (UTF-16) and UNIVERSALSTRING (UTF-32), and by summing per-character byte counts for UTF8STRING. The calculation overflows when the input reaches around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30 characters) the size wraps to zero, OPENSSL_malloc(1) is called, and the subsequent character copy writes several gigabytes past the one-byte allocation. X.509 certificate processing routes through ASN1_STRING_set_by_NID(), whose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID size limits cap the input length; no network protocol or certificate-handling path in OpenSSL exercises the overflow. Triggering the bug requires an application that calls ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly,
Betroffene Produkte
- openssl openssl
Quellen
- https://github.com/openssl/openssl/commit/4f8d2bddaa2c8e06f9c33390ee1717059a6e4be6
- https://github.com/openssl/openssl/commit/80c15faaf78042bbb8654a0e234c50c381732f74
- https://github.com/openssl/openssl/commit/bd17511070fb39a67bfa19682affb765e706a974
- https://github.com/openssl/openssl/commit/c332adaced43bcbb85f97410597e951c11ec3083
- https://github.com/openssl/openssl/commit/d32350ae8ef7426718f5aa9e383d4b51398ee255
- https://openssl-library.org/news/secadv/20260609.txt
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