Cyber Resilience

CVE-2026-34183

Openssl 3.4.0 – 3.4.6

Published
09 June 2026
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.010 62th percentile
Risk Priority 59 floored blend · peak EPSS

Summary

CVE-2026-34183 is a high-severity Improperly Controlled Sequential Memory Allocation (CWE-1325) vulnerability in Openssl Openssl. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked in the top 38% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-6 (Resource Availability) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-1325

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
T1499.003 Application Exhaustion Flood Impact
Adversaries may target resource intensive features of applications to cause a denial of service (DoS), denying availability to those applications.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-66199Same product: Openssl Openssl
CVE-2023-3446Same product: Openssl Openssl
CVE-2023-3817Same product: Openssl Openssl
CVE-2024-0727Same product: Openssl Openssl
CVE-2025-69420Same product: Openssl Openssl
CVE-2026-31790Same product: Openssl Openssl
CVE-2023-0217Same product: Openssl Openssl
CVE-2026-28390Same product: Openssl Openssl
CVE-2026-22795Same product: Openssl Openssl
CVE-2025-69421Same product: Openssl Openssl

Affected Assets

openssl
openssl
4.0.0 · 3.4.0 — 3.4.6 · 3.5.0 — 3.5.7 · 3.6.0 — 3.6.3

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V2.4.1
  • V13.1.2
  • V13.2.6

Mitigating Controls (NIST 800-53 r5) AI

SC-6 Resource Availability good match

SC-6 directly enforces resource quotas and priority allocations that stop unbounded sequential memory requests from exhausting the system.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require developers to enforce total memory limits during sequential allocations.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect unbounded allocation patterns, but removing the weakness does not fulfill testing obligations.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle includes resource-management requirements that can prevent uncontrolled per-object allocations.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles can mandate bounded resource usage, but eliminating this CWE does not address broader architectural controls.

A.8.28 Secure coding partial match
prevents

Secure coding standards can require explicit limits on memory per object, yet fixing the weakness alone does not satisfy the full control.

A.8.6 Capacity management partial match
mitigates

Capacity management directly limits total memory consumption across objects, mitigating unbounded sequential allocations.

References