جزئیات آسیب‌پذیری

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, or registers a custom string type via ASN1_STRING_TABLE_add(), with attacker-controlled input on the order of half a gigabyte or more. For these reasons this issue was assigned Low severity. The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

• https://openssl-library.org/news/secadv/20260609.txt vendor-advisory
• https://github.com/openssl/openssl/commit/d32350ae8ef7426718f5aa9e383d4b51398ee255 patch
• https://github.com/openssl/openssl/commit/c332adaced43bcbb85f97410597e951c11ec3083 patch
• https://github.com/openssl/openssl/commit/80c15faaf78042bbb8654a0e234c50c381732f74 patch
• https://github.com/openssl/openssl/commit/4f8d2bddaa2c8e06f9c33390ee1717059a6e4be6 patch
• https://github.com/openssl/openssl/commit/bd17511070fb39a67bfa19682affb765e706a974 patch