OpenSSL: Allocation of Resources Without Limits or Throttling
CVE-2026-14456 is a high-severity allocation of resources without limits or throttling vulnerability in OpenSSL, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 4.0.2, 3.6.4, 3.5.8 as the first without the flaw, so updating OpenSSL to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.73% chance of exploitation within 30 days, higher than 55% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update OpenSSL to 4.0.2 or 3.6.4 or 3.5.8, whichever matches your release line, or a later version.
- Read the advisory on openssl-library.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| OpenSSL | OpenSSL | 4.0.0 up to, but not including, 4.0.2; 3.6.0 up to, but not including, 3.6.4; 3.5.0 up to, but not including, 3.5.8 | 4.0.2, 3.6.4, 3.5.8 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CISA (ADP).
Official description
Issue summary: When an OpenSSL QUIC server (Listener SSL object) processes valid QUIC Initial packets for unknown destination connection IDs, it can allocate and queue new incoming channels without enforcing any limit. Impact summary: A remote peer that can make many Initial packets reach the server listener faster than the application accepts connections, can cause the memory allocated to store the per-channel state to grow without any limits, potentially making the QUIC listener unavailable and causing Denial of Service. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: The function that handles inbound QUIC packets uses Connection-Id from the packet header to find an existing connection (QUIC channel). If no existing connection is found and the packet type is INITIAL, the function treats the packet as a new connection. It allocates a new channel object and inserts it into a queue where it waits to be accepted by the local application with SSL_accept(3ossl). The memory occupied by these initial channel objects may grow without bounds if the application is not able to call SSL_accept() frequently enough to serve these inbound connection requests. The issue is present since OpenSSL 3.5 when the QUIC server implementation was added. The fix introduces a limit for pending connections. The default limit is set to 256 pending connections (waiting to be accepted by the local application). Applications may change the default by calling SSL_set_value_uint(3ossl). FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Allocation of Resources Without Limits or Throttling
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
How developers prevent this class of flaw
- Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
- Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More Allocation of Resources Without Limits or Throttling vulnerabilities (CWE-770)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Third-party and government advisories
- openwall.com/lists/oss-security/2026/08/13/4Mailing List, Third Party Advisory
Other vulnerabilities in OpenSSL
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Recent Allocation of Resources Without Limits or Throttling vulnerabilities
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