Skip to content

Issue summary: An uncommon configuration of clients...

High severity Unreviewed Published Apr 8, 2026 to the GitHub Advisory Database • Updated Apr 23, 2026

Package

No package listed— Suggest a package

Affected versions

Unknown

Patched versions

Unknown

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.

References

Published by the National Vulnerability Database Apr 7, 2026
Published to the GitHub Advisory Database Apr 8, 2026
Last updated Apr 23, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(14th percentile)

Weaknesses

Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer. Learn more on MITRE.

CVE ID

CVE-2026-28387

GHSA ID

GHSA-h2cc-wx97-xp8v

Source code

No known source code

Dependabot alerts are not supported on this advisory because it does not have a package from a supported ecosystem with an affected and fixed version.

Learn more about GitHub language support

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.