Security 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 64th percentile
Risk Priority 59 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

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 Application Exhaustion Flood (T1499.003); ranked in the top 36% 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

T1499.003 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 →
T1001.001 Junk Data Command And Control
Adversaries may add junk data to protocols used for command and control to make detection more difficult.
attack.mitre.org →
T1001.002 Steganography Command And Control
Adversaries may use steganographic techniques to hide command and control traffic to make detection efforts more difficult.
attack.mitre.org →
T1001.003 Protocol or Service Impersonation Command And Control
Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.
attack.mitre.org →
T1003.001 LSASS Memory Credential Access
Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS).
attack.mitre.org →
T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-3446Same product: Openssl Openssl
CVE-2026-45447Same product: Openssl Openssl
CVE-2025-15467Same product: Openssl Openssl
CVE-2023-3817Same product: Openssl Openssl
CVE-2023-5678Same product: Openssl Openssl
CVE-2023-6129Same product: Openssl Openssl
CVE-2025-11187Same product: Openssl Openssl
CVE-2026-28387Same product: Openssl Openssl
CVE-2016-6309Same product: Openssl Openssl
CVE-2026-84783Same 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

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 partial match
blocks

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.5.8 Information security in project management partial match
removes
A.8.25 Secure development life cycle partial match
blocks

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

A.8.26 Application security requirements partial match
removes
A.8.27 Secure system architecture and engineering principles partial match
blocks

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.8.29 Security testing in development and acceptance partial match
finds

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

References