CVE-2026-28387 Potential Use-after-free in DANE Client Code
A use-after-free in OpenSSL's DANE client code allows arbitrary code execution or crashes when specific TLSA record combinations are used.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-28387?
CVE-2026-28387 is a high-severity use after free vulnerability in Openssl Openssl, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-28387?
It affects 1 product.
Products include Openssl Openssl.
How do I fix CVE-2026-28387?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-28387 being exploited?
There is no known exploitation of CVE-2026-28387 in the wild and no public exploit code.
Other vulnerabilities in Openssl Openssl
Sources
Also known as ALPINE-CVE-2026-28387, AZL-81947, AZL-82103, BELL-CVE-2026-28387, CLSA-2026-1777455447, CLSA-2026-1777542789 and 11 more.