CVE-2026-28387: Potential Use-after-free in DANE Client Code
Issue summary: An uncommon configuration of clients performing DANE TLSA-based server authentication, when paired with uncommon server DANE TLSA records, may result in a use-after-free and/or double-free on the client side.
Impact summary: A use after free can have a range of potential consequences such as the corruption of valid data, crashes or execution of arbitrary code.
However, the issue only affects clients that make use of TLSA records with both the PKIX-TA(0/PKIX-EE(1) certificate usages and the DANE-TA(2) certificate usage.
By far the most common deployment of DANE is in SMTP MTAs for which RFC7672 recommends that clients treat as 'unusable' any TLSA records that have the PKIX certificate usages. These SMTP (or other similar) clients are not vulnerable to this issue. Conversely, any clients that support only the PKIX usages, and ignore the DANE-TA(2) usage are also not vulnerable.
The client would also need to be communicating with a server that publishes a TLSA RRset with both types of TLSA records.
No FIPS modules are affected by this issue, the problem code is outside the FIPS module boundary.
Other sources
Potential Use-after-free in DANE Client Code
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 3.3.7-2 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 1.1.1k-40 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 3.3.7-1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-28387?
CVE-2026-28387 is classified as a high severity vulnerability due to the potential for use-after-free and double-free scenarios.
What software is affected by CVE-2026-28387?
CVE-2026-28387 affects various versions of OpenSSL, including versions between 1.1.1 and 3.6.2.
How do I fix CVE-2026-28387?
To mitigate CVE-2026-28387, it is recommended to upgrade to the latest patched version of OpenSSL provided by your vendor.
What type of vulnerability is CVE-2026-28387?
CVE-2026-28387 is a use-after-free vulnerability that can lead to memory corruption.
How does CVE-2026-28387 impact DANE TLSA-based server authentication?
CVE-2026-28387 can cause security issues in clients performing DANE TLSA-based server authentication when paired with improper server configurations.