CVE-2026-72317
SUNRPC: pin upper rpc_clnt across the TLS connect_worker
Description
In the Linux kernel, the following vulnerability has been resolved: SUNRPC: pin upper rpc_clnt across the TLS connect_worker The TLS connect path has a use-after-free: nothing pins the upper rpc_clnt across the delayed connect_worker. xs_connect() stores task->tk_client in sock_xprt::clnt as a raw pointer and queues the worker; for TLS-secured transports that worker is xs_tcp_tls_setup_socket(), which reads several fields out of the saved pointer (cl_timeout, cl_program, cl_prog, cl_vers, cl_cred, cl_stats) to construct the args for the inner handshake rpc_clnt. The xprt does not reference the rpc_clnt; the rpc_clnt references the xprt. xs_destroy() does cancel the connect_worker, but it runs only when the xprt's refcount drops to zero, which cannot happen until the rpc_clnt releases its cl_xprt reference in rpc_free_client_work(). When a TLS handshake fails fatally (for example, an mTLS mount whose client cert does not match the server), the connecting task is woken with -EACCES and exits, the mount caller invokes rpc_shutdown_client(), and the upper rpc_clnt is freed before the queued connect_worker fires. xs_tcp_tls_setup_socket() then dereferences the freed clnt, producing the refcount_t underflow Michael Nemanov reported. Take a reference on the upper rpc_clnt in xs_connect() for TLS transports via a new rpc_hold_client() helper, and drop it in the connect_worker's exit path with rpc_release_client(). The xprt_lock_connect() / xprt_unlock_connect() pairing already serialises xs_connect() with xs_tcp_tls_setup_socket(), so the take and release are balanced one-for-one. The non-TLS connect worker (xs_tcp_setup_socket) never reads sock_xprt::clnt, so leave that path alone and avoid the clnt-holds-xprt-holds-clnt cycle that would otherwise prevent xprt destruction.
INFO
Published Date :
Aug. 15, 2026, 6:22 a.m.
Last Modified :
Aug. 17, 2026, 6:18 a.m.
Remotely Exploit :
Yes !
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Take reference on upper rpc_clnt in xs_connect.
- Drop reference in connect_worker exit path.
- Use rpc_hold_client() and rpc_release_client() helpers.
- Ensure balanced reference count for TLS transports.
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-2026-72317.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-72317 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-2026-72317
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-2026-72317 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-72317 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.
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CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '79cd550f8c884523b604fbfa43eb02def74d6224', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '7a65b41b657b71d5a77861f47dd13eb4bc8e10d0', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '5b0427ba582d143a364301f825f4e32272f06d2d', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': 'd49f6d098ed48775b9d27a9f9c5c220fdf76f102', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '46bc86c833956219bbfd246c1ffd832a479c5199', 'versionType': 'git'}], 'programFiles': ['include/linux/sunrpc/clnt.h', 'net/sunrpc/clnt.c', 'net/sunrpc/xprtsock.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.5'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.5', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/linux/sunrpc/clnt.h', 'net/sunrpc/clnt.c', 'net/sunrpc/xprtsock.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '79cd550f8c884523b604fbfa43eb02def74d6224', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '7a65b41b657b71d5a77861f47dd13eb4bc8e10d0', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '5b0427ba582d143a364301f825f4e32272f06d2d', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': 'd49f6d098ed48775b9d27a9f9c5c220fdf76f102', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '46bc86c833956219bbfd246c1ffd832a479c5199', 'versionType': 'git'}], 'programFiles': ['include/linux/sunrpc/clnt.h', 'net/sunrpc/clnt.c', 'net/sunrpc/xprtsock.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.5'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.5', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/linux/sunrpc/clnt.h', 'net/sunrpc/clnt.c', 'net/sunrpc/xprtsock.c'], 'defaultStatus': 'affected'}] -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 15, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '79cd550f8c884523b604fbfa43eb02def74d6224', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '7a65b41b657b71d5a77861f47dd13eb4bc8e10d0', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '5b0427ba582d143a364301f825f4e32272f06d2d', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': 'd49f6d098ed48775b9d27a9f9c5c220fdf76f102', 'versionType': 'git'}, {'status': 'affected', 'version': '75eb6af7acdf566c68d61e98e67ee2f235201c02', 'lessThan': '46bc86c833956219bbfd246c1ffd832a479c5199', 'versionType': 'git'}], 'programFiles': ['include/linux/sunrpc/clnt.h', 'net/sunrpc/clnt.c', 'net/sunrpc/xprtsock.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.5'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.5', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/linux/sunrpc/clnt.h', 'net/sunrpc/clnt.c', 'net/sunrpc/xprtsock.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: SUNRPC: pin upper rpc_clnt across the TLS connect_worker The TLS connect path has a use-after-free: nothing pins the upper rpc_clnt across the delayed connect_worker. xs_connect() stores task->tk_client in sock_xprt::clnt as a raw pointer and queues the worker; for TLS-secured transports that worker is xs_tcp_tls_setup_socket(), which reads several fields out of the saved pointer (cl_timeout, cl_program, cl_prog, cl_vers, cl_cred, cl_stats) to construct the args for the inner handshake rpc_clnt. The xprt does not reference the rpc_clnt; the rpc_clnt references the xprt. xs_destroy() does cancel the connect_worker, but it runs only when the xprt's refcount drops to zero, which cannot happen until the rpc_clnt releases its cl_xprt reference in rpc_free_client_work(). When a TLS handshake fails fatally (for example, an mTLS mount whose client cert does not match the server), the connecting task is woken with -EACCES and exits, the mount caller invokes rpc_shutdown_client(), and the upper rpc_clnt is freed before the queued connect_worker fires. xs_tcp_tls_setup_socket() then dereferences the freed clnt, producing the refcount_t underflow Michael Nemanov reported. Take a reference on the upper rpc_clnt in xs_connect() for TLS transports via a new rpc_hold_client() helper, and drop it in the connect_worker's exit path with rpc_release_client(). The xprt_lock_connect() / xprt_unlock_connect() pairing already serialises xs_connect() with xs_tcp_tls_setup_socket(), so the take and release are balanced one-for-one. The non-TLS connect worker (xs_tcp_setup_socket) never reads sock_xprt::clnt, so leave that path alone and avoid the clnt-holds-xprt-holds-clnt cycle that would otherwise prevent xprt destruction. Added Reference https://git.kernel.org/stable/c/46bc86c833956219bbfd246c1ffd832a479c5199 Added Reference https://git.kernel.org/stable/c/5b0427ba582d143a364301f825f4e32272f06d2d Added Reference https://git.kernel.org/stable/c/79cd550f8c884523b604fbfa43eb02def74d6224 Added Reference https://git.kernel.org/stable/c/7a65b41b657b71d5a77861f47dd13eb4bc8e10d0 Added Reference https://git.kernel.org/stable/c/d49f6d098ed48775b9d27a9f9c5c220fdf76f102