CVE-2026-75804Network attack vectorHinoki check available

Memory exhaustion via unchecked QUIC connection flow control

Published Sep 29, 2026 · Updated Sep 29, 2026

Resource exhaustion in the OpenSSL QUIC stack allows remote attackers to force excess heap allocation via crafted STREAM frames. The ossl_quic_rxfc_get_error() path reports stream errors but fails to propagate the parent connection flow-control error, so per-stream-compliant frames bypass the connection receive limit. Exploitation requires several streams that each stay within their stream window and omit offset-zero data; heap use can reach about 100 MB per connection instead of the 768 KiB default window.

CVSS severityUnavailable
Unscored
EPSS probability0.35%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Resource exhaustion in the OpenSSL QUIC stack allows remote attackers to force excess heap allocation via crafted STREAM frames. The ossl_quic_rxfc_get_error() path reports stream errors but fails to propagate the parent connection flow-control error, so per-stream-compliant frames bypass the connection receive limit. Exploitation requires several streams that each stay within their stream window and omit offset-zero data; heap use can reach about 100 MB per connection instead of the 768 KiB default window.

The record

CVE
CVE-2026-75804
Published
Sep 29, 2026
Updated
Sep 29, 2026
Vendor
OpenSSL Project
Product
OpenSSL
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.4.0 <3.4.8
  2. Affected versionversion=3.5.0 <3.5.9
  3. Affected versionversion=3.6.0 <3.6.5
  4. Affected versionversion=4.0.0 <4.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenSSL Project · OpenSSLversion=3.4.0 <3.4.8; version=3.5.0 <3.5.9; version=3.6.0 <3.6.5; version=4.0.0 <4.0.3

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Endpoint Denial of Service: Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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