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OpenSSLFramework / library

CVE-2026-34183

HIGH · 7.5 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 3.4.6 / 3.5.7 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: Remote peer may exhaust heap memory of the QUIC server or client by flooding it with packets containing PATH_CHALLENGE frames. Impact summary: A malicious remote peer can cause an unbounded memory allocation which can lead to an abnormal termination of the application acting as a QUIC client or server and a Denial of Service. A remote peer may exhaust heap memory by flooding the local QUIC stack with PATH_CHALLENGE frames. The local QUIC stack allocates a PATH_RESPONSE frame for every PATH_CHALLENGE it receives. The allocated PATH_RESPONSE frame gets freed only when the remote peer acknowledges reception of the PATH_RESPONSE frame which will not be done by a malicious peer. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue. The QUIC stack is outside of 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

A detailed technical summary for this CVE is being prepared.

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:>= 3.4.0, < 3.4.6>= 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 3.4.6 / 3.5.7 / 3.6.3 or later
Fixed in 3.4.63.5.73.6.3
Vendor patch github.com →
Recommended fix High confidence

OpenSSL 3.4.6, 3.5.7, 3.6.3, or 4.0.1 (depending on your current major.minor branch)

  1. 1. Identify the current OpenSSL version in use by running `openssl version` or checking your application's dependencies.
  2. 2. If running OpenSSL 3.4.x (versions 3.4.0-3.4.5), upgrade to OpenSSL 3.4.6 or later.
  3. 3. If running OpenSSL 3.5.x (versions 3.5.0-3.5.6), upgrade to OpenSSL 3.5.7 or later.
  4. 4. If running OpenSSL 3.6.x (versions 3.6.0-3.6.2), upgrade to OpenSSL 3.6.3 or later.
  5. 5. If running OpenSSL 4.0.0, upgrade to OpenSSL 4.0.1 or later.
  6. 6. After upgrading, verify the new version with `openssl version` and ensure your QUIC client/server applications are functioning correctly.
  7. 7. Rebuild or restart any services that link against the OpenSSL library to ensure they use the patched version.
Caveat Upgrading OpenSSL may require recompiling applications that link against it; verify compatibility with your application stack before deploying in production.

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 $1,950. 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-2026-34183 in production — separate from our analysis above.

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What this is

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