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CVE-2026-25833 Mbed TLS CVE debrief

CVE-2026-25833 is a HIGH severity vulnerability in Mbed TLS, a cryptographic library. The vulnerability is caused by a buffer overflow in the x509_inet_pton_ipv6() function. It affects Mbed TLS versions from 3.5.0 to 3.6.5 and 4.0.0. The vulnerability was published on [cvePublishedAt] and last modified on [cveModifiedAt].

Vendor
Mbed TLS
Product
Mbed TLS
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-01
Original CVE updated
2026-06-05
Advisory published
2026-04-01
Advisory updated
2026-06-05

Who should care

Users of Mbed TLS, especially those using versions 3.5.0 to 3.6.5 and 4.0.0, should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by a buffer overflow in the x509_inet_pton_ipv6() function in Mbed TLS. This function is used for parsing IPv6 addresses. The buffer overflow can be exploited remotely, allowing an attacker to potentially execute arbitrary code or cause a denial of service.

Defensive priority

HIGH

Recommended defensive actions

  • Upgrade to Mbed TLS version 3.6.6 or 4.1.0, which fixes the vulnerability.
  • Refer to [ref-4] and [ref-5] for vendor advisories and mitigation strategies.

Evidence notes

The vulnerability has a CVSS score of 7.5 and is classified as HIGH severity. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Official resources

CVE-2026-25833 was published on 2026-04-01T19:16:28.530Z and last modified on 2026-06-05T19:38:32.047Z.