High

Potential Use-After-Free in OpenSSL DANE Client Code

IdentifiersCVE-2026-28387CWE-416· Use After Free

CVE-2026-28387 is a low-severity memory-safety flaw in OpenSSL's DANE client processing. Under an uncommon client configuration that performs DANE TLSA-based server authentication, a server TLSA RRset containing both PKIX certificate usages (PKIX-TA(0) and/or PKIX-EE(1)) and DANE-TA(2) certificate usage can trigger a client-side use-after-free and/or double-free condition. The issue is limited to clients that process both of those TLSA usage classes together; clients that treat PKIX usages as unusable per RFC 7672 guidance, such as typical SMTP MTAs, are not affected, and clients that support only PKIX usages while ignoring DANE-TA(2) are also not vulnerable. The vulnerable code is outside the OpenSSL FIPS module boundary.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can corrupt memory in the client process and may lead to application crashes or other denial-of-service conditions. As with use-after-free flaws generally, the consequences can extend to corruption of valid data and potentially arbitrary code execution, although the provided information does not confirm practical code-execution exploitability for this specific issue. The issue affects the client side only.

Mitigation

If you can’t patch tonight, do this now.

Avoid vulnerable DANE client behavior by not processing mixed TLSA RRsets that combine PKIX usages with DANE-TA(2), where operationally feasible. SMTP MTAs that follow RFC 7672 guidance and treat PKIX TLSA usages as unusable are not vulnerable. Clients that ignore DANE-TA(2) and support only PKIX usages are also not vulnerable. More generally, disable or avoid DANE TLSA-based authentication in affected clients until patched if exposure cannot otherwise be constrained.

Remediation

Patch, then assume compromise.

Upgrade OpenSSL to a fixed release. According to the provided content, fixes are included in OpenSSL 3.6.2, 3.5.6, 3.4.5, 3.3.7, 3.0.20, and 1.1.1zg. OpenSSL 1.0.2 is not affected. Downstream distributions should consume the corresponding vendor-updated packages.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

OpenSSL Software FoundationOpensslapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

17 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

17 SOURCESView more in app

alpinelinuxNews

Apr 15, 2026

Alpine Linue stable releases 3.20.10, 3.21.7, 3.22.4, 3.23.4 | Alpine Linux

A specific vulnerability in OpenSSL addressed in Alpine Linux stable releases 3.20.10, 3.21.7, 3.22.4, and 3.23.4.

help net securityNews

Apr 8, 2026

OpenSSL 3.6.2 lands with eight CVE fixes - Help Net Security

A potential use-after-free in DANE client code in OpenSSL.

cyberthroneNews

Apr 8, 2026

OpenSSL 3.6.2: The Moderate Severity Wave - TheCyberThrone

A potential use-after-free in OpenSSL DANE client code that can expose affected applications to denial-of-service conditions when processing crafted input.

openssl libraryNews

Apr 7, 2026

OpenSSL Release Announcement for 3.6.2, 3.5.6, 3.4.5, 3.3.7, 3.0.20, 1.1.1zg and 1.0.2zp | OpenSSL Library

Potential use-after-free in OpenSSL DANE client code.

+1 more in the timeline

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity11