Heap-based buffer overflow in OpenSSL - CVE-2026-7383
Published: June 10, 2026
Vulnerability identifier: #VU134276
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-7383
CWE-ID: CWE-122
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: OpenSSL Software Foundation
Affected software:
OpenSSL
OpenSSL
Detailed vulnerability description
The vulnerability allows a local user to execute arbitrary code.
The vulnerability exists due to heap-based buffer overflow in ASN1_mbstring_copy() and ASN1_mbstring_ncopy() when converting attacker-controlled multibyte strings to Unicode output. A local user can supply extremely large crafted input to execute arbitrary code.
Triggering the issue requires direct use of ASN1_mbstring_copy() or ASN1_mbstring_ncopy(), or a custom string type registered via ASN1_STRING_TABLE_add(), with attacker-controlled input on the order of half a gigabyte or more.
How to mitigate CVE-2026-7383
Install security update from vendor's website.