#VU124806 Buffer underflow in mbed TLS - CVE-2026-25833
Published: April 2, 2026
Vulnerability identifier: #VU124806
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-25833
CWE-ID: CWE-124
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
mbed TLS
mbed TLS
Software vendor:
ARM
ARM
Description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper input validation in x509_inet_pton_ipv6() when parsing IPv6 address input. A remote attacker can send a specially crafted IPv6 address string to cause a buffer underread of up to 4 bytes, potentially leading to a denial of service.
In rare cases, the buffer underread may cross a page boundary and trigger a memory access violation, resulting in a crash.
Remediation
Install security update from vendor's website.