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OpenSSLFramework / library

CVE-2026-42764

HIGH · 7.5 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 3.5.7 / 3.6.3 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Issue summary: Receiving a QUIC initial packet with an invalid token may trigger a NULL pointer dereference in the OpenSSL QUIC server with address validation disabled. Impact summary: NULL pointer dereference typically causes abnormal termination of the affected QUIC server process and a Denial of Service. If the address validation is disabled in the OpenSSL QUIC server implementation, an attacker can crash the server by sending an initial packet with an invalid or expired token. By default, the client address validation is enabled in the OpenSSL QUIC server implementation, which makes the default configuration not vulnerable to this issue. However if the SSL_LISTENER_FLAG_NO_VALIDATE is used with the SSL_new_listener() call, the address validation is disabled making the vulnerable code reachable. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OpenSSLFramework / library
Affected:>= 3.5.0, < 3.5.7>= 3.6.0, < 3.6.3= 4.0.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.5.7 / 3.6.3 or later
Fixed in 3.5.73.6.3
Vendor patch github.com →
Recommended fix High confidence

OpenSSL 3.5.7, 3.6.3, or 4.0.1 (depending on your current branch)

  1. 1. Identify the current OpenSSL version in use by running `openssl version` or checking your application's dependencies.
  2. 2. For applications using OpenSSL QUIC server with SSL_LISTENER_FLAG_NO_VALIDATE, plan an immediate upgrade.
  3. 3. Upgrade to OpenSSL 3.5.7 if using 3.5.x, or upgrade to 3.6.3 if using 3.6.x, or upgrade to 4.0.1 if using 4.0.0.
  4. 4. After upgrading, verify the new version is active using `openssl version`.
  5. 5. Test QUIC server functionality to confirm the fix works correctly.
  6. 6. Alternatively, if upgrading is not immediately feasible, ensure SSL_LISTENER_FLAG_NO_VALIDATE is not used, as the default configuration with address validation enabled is not vulnerable.
Caveat Major version upgrades (e.g., 3.x to 4.x) may introduce API/ABI changes; review OpenSSL release notes for breaking changes

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42764 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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