CVE-2026-11941
Use-after-free in connection ID iterator and FFI functions
Cloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions.
The “quiche_connection_id_iter_next” and “quiche_conn_retired_scid_next” functions would return a pointer to a “ConnectionId” to the applications via function arguments, but the owned “ConnectionId” would be dropped at the end of those functions' scope.
Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag.
Impact If unpatched, an application calling the affected FFI functions will dereference freed memory. The most likely outcome is undefined behavior leading to a process crash (denial of service). Depending on allocator state, the read may also return adjacent heap contents, resulting in limited information disclosure or incorrect connection identifier handling.
Mitigation Users are requested to upgrade to quiche 0.29.2 which is the earliest version containing the fix for this issue.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
Use-after-free in connection ID iterator and FFI functions
Cloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions.
The “quiche_connection_id_iter_next” and “quiche_conn_retired_scid_next” functions would return a pointer to a “ConnectionId” to the applications via function arguments, but the owned “ConnectionId” would be dropped at the end of those functions' scope.
Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag.
Impact If unpatched, an application calling the affected FFI functions will dereference freed memory. The most likely outcome is undefined behavior leading to a process crash (denial of service). Depending on allocator state, the read may also return adjacent heap contents, resulting in limited information disclosure or incorrect connection identifier handling.
Mitigation Users are requested to upgrade to quiche 0.29.2 which is the earliest version containing the fix for this issue.
- Record
CVE-2026-11941- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-416
- Updated
- 2026-11-02
EUVDEUVD-2026-38003
Cloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions.
The “quiche_connection_id_iter_next” and “quiche_conn_retired_scid_next” functions would return a pointer to a “ConnectionId” to the applications via function arguments, but the owned “ConnectionId” would be dropped at the end of those functions' scope.
Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag.
Impact If unpatched, an application calling the affected FFI functions will dereference freed memory. The most likely outcome is undefined behavior leading to a process crash (denial of service). Depending on allocator state, the read may also return adjacent heap contents, resulting in limited information disclosure or incorrect connection identifier handling.
Mitigation Users are requested to upgrade to quiche 0.29.2 which is the earliest version containing the fix for this issue.
- Record
EUVD-2026-38003- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-mh64-ph39-mrc9
Cloudflare Quiche: Use-after-free in connection ID iterator FFI functions
Impact
Cloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions.
The quiche_connection_id_iter_next and quiche_conn_retired_scid_next functions would return a pointer to a ConnectionId to the applications via function arguments, but the the owned ConnectionId would be dropped at the end of those functions' scope.
Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag.
quiche 0.29.2 is the earliest version containing the fix for this issue.
- Record
GHSA-mh64-ph39-mrc9- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-416
- Updated
- 2026-11-02
NVD
Cloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions.
The “quiche_connection_id_iter_next” and “quiche_conn_retired_scid_next” functions would return a pointer to a “ConnectionId” to the applications via function arguments, but the owned “ConnectionId” would be dropped at the end of those functions' scope.
Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag.
Impact If unpatched, an application calling the affected FFI functions will dereference freed memory. The most likely outcome is undefined behavior leading to a process crash (denial of service). Depending on allocator state, the read may also return adjacent heap contents, resulting in limited information disclosure or incorrect connection identifier handling.
Mitigation Users are requested to upgrade to quiche 0.29.2 which is the earliest version containing the fix for this issue.
- Record
CVE-2026-11941- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-416
- Updated
- 2026-11-02
OSV
Use-after-free in connection ID iterator and FFI functions
Cloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions.
The “quiche_connection_id_iter_next” and “quiche_conn_retired_scid_next” functions would return a pointer to a “ConnectionId” to the applications via function arguments, but the owned “ConnectionId” would be dropped at the end of those functions' scope.
Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag.
Impact If unpatched, an application calling the affected FFI functions will dereference freed memory. The most likely outcome is undefined behavior leading to a process crash (denial of service). Depending on allocator state, the read may also return adjacent heap contents, resulting in limited information disclosure or incorrect connection identifier handling.
Mitigation Users are requested to upgrade to quiche 0.29.2 which is the earliest version containing the fix for this issue.
- Record
CVE-2026-11941- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-416
- Updated
- 2026-11-02
OSVGHSA-mh64-ph39-mrc9
Cloudflare Quiche: Use-after-free in connection ID iterator FFI functions
Impact
Cloudflare Quiche was affected by 2 use-after-free vulnerabilities in the connection ID iterator FFI functions.
The quiche_connection_id_iter_next and quiche_conn_retired_scid_next functions would return a pointer to a ConnectionId to the applications via function arguments, but the the owned ConnectionId would be dropped at the end of those functions' scope.
Only applications using those FFI functions are affected. The FFI API is disabled by default by a build-time feature flag.
quiche 0.29.2 is the earliest version containing the fix for this issue.
- Record
GHSA-mh64-ph39-mrc9- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-416
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
quichecrates.io |
0.20.0 up to 0.29.2 | 0.29.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-11941 is a medium vulnerability (CVSS 5.6) in Cloudflare Quiche, published June 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.25%, the 16th percentile. Fixed in quiche 0.29.2.