CVE-2026-11941Network attack vector

Process crash via dangling FFI pointers

Published Jun 19, 2026 · Updated Jun 19, 2026

Use-after-free flaws in Cloudflare quiche 0.20.0 through 0.29.1 allow remote attackers to crash processes via affected C FFI calls. quiche_connection_id_iter_next returns a pointer after dropping the cloned connection ID's backing storage, while quiche_conn_retired_scid_next exposes a retired source ID after its owner is dropped. Only applications built with the nondefault ffi feature and invoking these functions are exposed; dereferencing the pointers can crash the process, disclose adjacent heap contents, or mishandle connection IDs.

CVSS severity5.6
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free flaws in Cloudflare quiche 0.20.0 through 0.29.1 allow remote attackers to crash processes via affected C FFI calls. quiche_connection_id_iter_next returns a pointer after dropping the cloned connection ID's backing storage, while quiche_conn_retired_scid_next exposes a retired source ID after its owner is dropped. Only applications built with the nondefault ffi feature and invoking these functions are exposed; dereferencing the pointers can crash the process, disclose adjacent heap contents, or mishandle connection IDs.

The record

CVE
CVE-2026-11941
Published
Jun 19, 2026
Updated
Jun 19, 2026
Vendor
Cloudflare
Product
quiche
Classifications
CWE-416
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 19, 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=0.20.0 <=0.29.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cloudflare · quicheversion=0.20.0 <=0.29.1

Published CVSS scores

5.6CloudflareCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

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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