CVE-2026-10655
Use-after-free race in SNTP async client when closing the socket while the socket service is still polling it
Description
The asynchronous SNTP client in Zephyr (subsys/net/lib/sntp/sntp.c, sntp_close_async) closed the UDP socket file descriptor directly from the calling thread immediately after detaching it from the network socket service, without synchronizing with the socket-service poll thread. The socket service thread polls each socket via zvfs_poll, which (in zsock_poll_prepare_ctx) registers a k_poll_event pointing into the socket's net_context (&ctx->recv_q) and then blocks in k_poll without holding a reference or lock. net_context objects are allocated from a fixed pool (contexts[CONFIG_NET_MAX_CONTEXTS]) and reused after close. When sntp_close_async is invoked from a different thread than the poll thread (in the in-tree consumer subsys/net/lib/config/init_clock_sntp.c, the SNTP timeout handler runs on the system workqueue while the socket service thread is blocked in poll on the same fd), the close frees and may reuse the net_context while the poll thread still has a poller node linked into the freed object, resulting in a use-after-free / object confusion of kernel poll structures. The SNTP timeout path is the normal no-response failure mode, so a network peer or off-path attacker who drops or delays the SNTP/NTP response can drive the racing close repeatedly (and periodically with NET_CONFIG_SNTP_INIT_RESYNC). The most likely consequence is a crash of the networking thread (denial of service), with potential memory corruption when the freed context slot is reallocated. The fix defers the close to the socket service thread itself via net_socket_service_close (NET_SOCKET_SERVICE_CLOSE_SOCKETS), so the same thread that polls performs the close, eliminating the race. Affected releases: v4.2.0 through v4.4.0.
INFO
Published Date :
June 30, 2026, 5:16 p.m.
Last Modified :
Oct. 25, 2026, 9:10 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-10655
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | e2e69745-5e70-4e92-8431-deb5529a81ad | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Apply the vendor patch to sntp.c.
- Defer socket closing to the socket service thread.
- Ensure thread synchronization for socket operations.
- Update affected Zephyr releases.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-10655.
| URL | Resource |
|---|---|
| https://github.com/zephyrproject-rtos/zephyr/commit/ef47bdf328b4206ac3b3922ec09184f7a6f7412a | Patch |
| https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-34wr-cg29-c4mw | Exploit Patch Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-10655 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-10655
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-10655 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-10655 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 25, 2026
Action Type Old Value New Value Added Translation Title: zephyr de zephyrproject, Description: El cliente SNTP asíncrono en Zephyr (subsys/net/lib/sntp/sntp.c, sntp_close_async) cerró el descriptor de archivo del socket UDP directamente desde el hilo llamador inmediatamente después de desvincularlo del servicio de sockets de red, sin sincronizarse con el hilo de sondeo del servicio de sockets. El hilo del servicio de sockets sondea cada socket a través de zvfs_poll, el cual (en zsock_poll_prepare_ctx) registra un k_poll_event apuntando al net_context del socket (&ctx -> recv_q) y luego se bloquea en k_poll sin mantener una referencia o un bloqueo. Los objetos net_context se asignan de un pool fijo (contexts[CONFIG_NET_MAX_CONTEXTS]) y se reutilizan después del cierre. Cuando sntp_close_async es invocado desde un hilo diferente al hilo de sondeo (en el consumidor in-tree subsys/net/lib/config/init_clock_sntp.c, el gestor de tiempo de espera SNTP se ejecuta en la cola de trabajo del sistema mientras el hilo del servicio de sockets está bloqueado en el sondeo en el mismo fd), el cierre libera y puede reutilizar el net_context mientras el hilo de sondeo todavía tiene un nodo de sondeo vinculado al objeto liberado, lo que resulta en un uso después de liberación / confusión de objetos de las estructuras de sondeo del kernel. La ruta de tiempo de espera SNTP es el modo de fallo normal sin respuesta, por lo que un par de red o un atacante fuera de ruta que descarta o retrasa la respuesta SNTP/NTP puede impulsar el cierre en carrera repetidamente (y periódicamente con NET_CONFIG_SNTP_INIT_RESYNC). La consecuencia más probable es un fallo del hilo de red (denegación de servicio), con potencial corrupción de memoria cuando el slot de contexto liberado es reasignado. La solución aplaza el cierre al propio hilo del servicio de sockets a través de net_socket_service_close (NET_SOCKET_SERVICE_CLOSE_SOCKETS), por lo que el mismo hilo que sondea realiza el cierre, eliminando la condición de carrera. Versiones afectadas: v4.2.0 a v4.4.0. -
CVE Modified by [email protected]
Oct. 15, 2026
Action Type Old Value New Value Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/10xxx/CVE-2026-10655.json">CVE-2026-10655</a> Added Reference https://github.com/zephyrproject-rtos/zephyr/commit/ef47bdf328b4206ac3b3922ec09184f7a6f7412a Added Reference https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-34wr-cg29-c4mw Removed Reference https://github.com/zephyrproject-rtos/zephyr/commit/ef47bdf328b4206ac3b3922ec09184f7a6f7412a Removed Reference https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-34wr-cg29-c4mw Removed Reference Type https://github.com/zephyrproject-rtos/zephyr/commit/ef47bdf328b4206ac3b3922ec09184f7a6f7412a Types: Patch Removed Reference Type https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-34wr-cg29-c4mw Types: Exploit, Patch, Vendor Advisory -
CVE Modified by [email protected]
Jul. 14, 2026
Action Type Old Value New Value Changed Affected [{'vendor': 'zephyrproject', 'product': 'zephyr', 'versions': [{'status': 'affected', 'version': '4.2.0', 'lessThan': '4.5.0', 'versionType': 'semver'}], 'packageName': 'zephyr', 'collectionURL': 'https://github.com/zephyrproject-rtos/zephyr', 'defaultStatus': 'unaffected'}] [{'vendor': 'zephyrproject', 'product': 'zephyr', 'versions': [{'status': 'affected', 'version': '4.2.0', 'lessThan': '4.5.0', 'versionType': 'semver'}], 'packageName': 'zephyr', 'programFiles': ['subsys/net/lib/sntp/sntp.c'], 'collectionURL': 'https://github.com/zephyrproject-rtos/zephyr', 'defaultStatus': 'unaffected'}] -
Initial Analysis by [email protected]
Jul. 06, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:o:zephyrproject:zephyr:*:*:*:*:*:*:*:* versions from (including) 4.2.0 up to (including) 4.4.1 Added Reference Type Zephyr Project: https://github.com/zephyrproject-rtos/zephyr/commit/ef47bdf328b4206ac3b3922ec09184f7a6f7412a Types: Patch Added Reference Type Zephyr Project: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-34wr-cg29-c4mw Types: Exploit, Patch, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 30, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-10655', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-30T16:41:42.494668Z'} -
New CVE Received by [email protected]
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'zephyrproject', 'product': 'zephyr', 'versions': [{'status': 'affected', 'version': '4.2.0', 'lessThan': '4.5.0', 'versionType': 'semver'}], 'packageName': 'zephyr', 'collectionURL': 'https://github.com/zephyrproject-rtos/zephyr', 'defaultStatus': 'unaffected'}] Added Description The asynchronous SNTP client in Zephyr (subsys/net/lib/sntp/sntp.c, sntp_close_async) closed the UDP socket file descriptor directly from the calling thread immediately after detaching it from the network socket service, without synchronizing with the socket-service poll thread. The socket service thread polls each socket via zvfs_poll, which (in zsock_poll_prepare_ctx) registers a k_poll_event pointing into the socket's net_context (&ctx->recv_q) and then blocks in k_poll without holding a reference or lock. net_context objects are allocated from a fixed pool (contexts[CONFIG_NET_MAX_CONTEXTS]) and reused after close. When sntp_close_async is invoked from a different thread than the poll thread (in the in-tree consumer subsys/net/lib/config/init_clock_sntp.c, the SNTP timeout handler runs on the system workqueue while the socket service thread is blocked in poll on the same fd), the close frees and may reuse the net_context while the poll thread still has a poller node linked into the freed object, resulting in a use-after-free / object confusion of kernel poll structures. The SNTP timeout path is the normal no-response failure mode, so a network peer or off-path attacker who drops or delays the SNTP/NTP response can drive the racing close repeatedly (and periodically with NET_CONFIG_SNTP_INIT_RESYNC). The most likely consequence is a crash of the networking thread (denial of service), with potential memory corruption when the freed context slot is reallocated. The fix defers the close to the socket service thread itself via net_socket_service_close (NET_SOCKET_SERVICE_CLOSE_SOCKETS), so the same thread that polls performs the close, eliminating the race. Affected releases: v4.2.0 through v4.4.0. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H Added CWE CWE-416 Added Reference https://github.com/zephyrproject-rtos/zephyr/commit/ef47bdf328b4206ac3b3922ec09184f7a6f7412a Added Reference https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-34wr-cg29-c4mw