Use After Free in OpenSSL
CVE-2026-28387
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.009 (59.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 60th percentile — 59.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.009 · change: +0.003
Affected products
- OpenSSL — versions 3.6.0, 3.5.0, 3.4.0
Weakness classification (CWE)
References
- openssl-library.org/news/secadv/20260407.txt (vendor-advisory, Vendor Advisory)
- github.com/openssl/openssl/commit/258a8f63b26995ba357f4326da00e19e29c6acbe (Patch, patch)
- github.com/openssl/openssl/commit/444958deaf450aea819171f97ae69eaedede42c3 (Patch, patch)
- github.com/openssl/openssl/commit/07e727d304746edb49a98ee8f6ab00256e1f012b (Patch, patch)
- github.com/openssl/openssl/commit/7a4e08cee62a728d32e60b0de89e6764339df0a7 (Patch, patch)
- github.com/openssl/openssl/commit/ec03fa050b3346997ed9c5fef3d0e16ad7db8177 (Patch, patch)
- 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
- 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Frequently asked questions
- What is CVE-2026-28387?
- CVE-2026-28387 is a high-severity vulnerability in OpenSSL, classified under Use After Free. CVSS score: 8.1/10. Published 2026-04-07.
- How severe is CVE-2026-28387?
- High severity. CVSS v3 base score is 8.1 out of 10.