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    <title>Most recent entries from all</title>
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    <lastBuildDate>Wed, 30 Sep 2026 07:54:16 +0000</lastBuildDate>
    <item>
      <title>CVE-2026-84783 — Use-After-Free in X.509 Extension Cache Under Concurrent Use</title>
      <link>https://db.gcve.eu/vuln/cve-2026-84783</link>
      <description>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; OpenSSL&lt;/p&gt;
&lt;p&gt;Issue summary: The first concurrent use of the same X.509 certificate by
several threads may cause its cached extension data to be freed while
another thread is still using it.&lt;/p&gt;
&lt;p&gt;Impact summary: A remote, unauthenticated peer could crash a multi-threaded
TLS client, or a multi-threaded TLS server that requests client
certificates, if the first certificate chains built to the same trusted CA
certificate are built by several connections at the same time. This is a
use-after-free read, which is likely to crash the process, resulting in a
Denial of Service.&lt;/p&gt;
&lt;p&gt;CWE: CWE-416: Use After Free&lt;/p&gt;
&lt;p&gt;Description: OpenSSL caches the decoded values of a certificate&amp;#39;s X.509v3
extensions inside the X509 object the first time they are needed. In
OpenSSL 4.0 this cache is built in two phases: the extension values are
computed while holding a read lock on the certificate, and the results are
then installed into the certificate under a write lock. Because a read lock
does not exclude other readers, several threads can compute the cache for
the same certificate at the same time. Each thread that subsequently
acquires the write lock installs its own results and frees the values
installed by the thread before it, even though that earlier thread has
already marked the cache as complete and may have returned pointers into it
to its caller. A caller still using those pointers then reads freed memory.&lt;/p&gt;
&lt;p&gt;Any certificate shared between threads is exposed the first time its
extensions are decoded. In TLS the ce…&lt;/p&gt;</description>
      <content:encoded>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; OpenSSL&lt;/p&gt;
&lt;p&gt;Issue summary: The first concurrent use of the same X.509 certificate by
several threads may cause its cached extension data to be freed while
another thread is still using it.&lt;/p&gt;
&lt;p&gt;Impact summary: A remote, unauthenticated peer could crash a multi-threaded
TLS client, or a multi-threaded TLS server that requests client
certificates, if the first certificate chains built to the same trusted CA
certificate are built by several connections at the same time. This is a
use-after-free read, which is likely to crash the process, resulting in a
Denial of Service.&lt;/p&gt;
&lt;p&gt;CWE: CWE-416: Use After Free&lt;/p&gt;
&lt;p&gt;Description: OpenSSL caches the decoded values of a certificate&amp;#39;s X.509v3
extensions inside the X509 object the first time they are needed. In
OpenSSL 4.0 this cache is built in two phases: the extension values are
computed while holding a read lock on the certificate, and the results are
then installed into the certificate under a write lock. Because a read lock
does not exclude other readers, several threads can compute the cache for
the same certificate at the same time. Each thread that subsequently
acquires the write lock installs its own results and frees the values
installed by the thread before it, even though that earlier thread has
already marked the cache as complete and may have returned pointers into it
to its caller. A caller still using those pointers then reads freed memory.&lt;/p&gt;
&lt;p&gt;Any certificate shared between threads is exposed the first time its
extensions are decoded. In TLS the ce…&lt;/p&gt;</content:encoded>
      <guid isPermaLink="false">https://db.gcve.eu/vuln/cve-2026-84783</guid>
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