medium CVSS 5.5

CVE-2023-52704·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: freezer,umh: Fix call_usermode_helper_exec() vs SIGKILL Tetsuo-San noted that commit f5d39b020809 ("freezer,sched: Rewrite core freezer logic") broke call_usermodehelper_exec() for the KILLABLE case. Specifically it was missed that the second, unconditional, wait_for_completion() was not optional and ensures the on-stack completion is unused before going out-of-scope.

Severity
medium
Software
Kernel
Fixed in
6.1.13
Published
2024-05-21

Affected versions

From: 6.1

Until: 6.1.13

Fixed in: 6.1.13

How to fix this CVE

Update your Linux kernel to version 6.1.13 or later to resolve a race condition in the usermode helper subsystem that could cause kernel panics. Systems running kernel versions 6.1 through 6.1.12 should prioritize this patch, as it corrects improper handling of completion signals during process termination. Apply the update using your distribution's package manager and reboot to activate the fixed kernel.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to check the currently running kernel version and confirm if it falls within 6.1.0 to 6.1.12
  2. Check /proc/version to verify the exact kernel build date and version string
  3. Review dmesg logs for recent kernel panic messages or call stack traces mentioning 'call_usermodehelper' or 'freezer' subsystem
  4. After patching, run 'uname -r' again and verify the kernel version is 6.1.13 or higher, then confirm no new panic messages appear in dmesg over 24 hours of operation

FAQ

What is CVE-2023-52704?

This vulnerability is a synchronization bug in the Linux kernel's usermode helper mechanism that improperly manages process completion signals, potentially causing kernel availability issues when helper processes receive termination signals.

Is CVE-2023-52704 being actively exploited?

No, this CVE is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits have been released. It is a logic error that requires local access to trigger.

What versions of Kernel are affected by CVE-2023-52704?

Linux kernel versions 6.1.0 through 6.1.12 are vulnerable. The fix was released in kernel 6.1.13.

How do I check if my server is vulnerable to CVE-2023-52704?

Run 'uname -r' and check if the output shows kernel version 6.1.0 to 6.1.12. If it does, your system is affected and requires an update to 6.1.13 or later.

Does Defensia detect CVE-2023-52704?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2023-52704 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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CVE-2026-64385CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-free in SMB2_ioctl() replay A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_ioctl_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.
CVE-2026-64391CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for ADS I/O Alternate data streams are stored as xattrs. Unlike regular file I/O, their read and write paths therefore call VFS xattr helpers which recheck inode permissions and LSM policy using the current task credentials. Run ADS I/O with the credentials captured when the SMB handle was opened.
CVE-2026-64383CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-free in SMB2_flush() replay SMB2_flush() keeps its response buffer bookkeeping across replay attempts. If a replayable flush response is received and the retry then fails before cifs_send_recv() stores a replacement response, flush_exit will free the stale response pointer a second time. Reinitialize resp_buftype and rsp_iov at the top of the replay loop so cleanup only acts on response state produced by the current attempt. This fixes a double-free without changing replay handling for successful requests.
CVE-2026-53176CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN In drivers/infiniband/ulp/isert/ib_isert.c, isert_login_recv_done() computes the login request payload length as wc->byte_len minus ISER_HEADERS_LEN with no lower bound, and login_req_len is a signed int. A remote iSER initiator can post a login Send work request carrying fewer than ISER_HEADERS_LEN (76) bytes, so the subtraction underflows and login_req_len becomes negative. isert_rx_login_req() then reads that negative length back into a signed int, takes size = min(rx_buflen, MAX_KEY_VALUE_PAIRS), and because the min() is signed it keeps the negative value; the value is then passed as the memcpy() length and sign-extended to a multi-gigabyte size_t. The copy into the 8192-byte login->req_buf runs far out of bounds and faults, crashing the target node. The login phase precedes iSCSI authentication, so no credentials are required to reach this path. Reject any login PDU shorter than ISER_HEADERS_LEN before the subtraction, mirroring the existing early return on a failed work completion, so login_req_len can never go negative. The upper bound was already safe: a posted login buffer cannot deliver more than ISER_RX_PAYLOAD_SIZE, so the difference stays at or below MAX_KEY_VALUE_PAIRS and the existing min() clamps it; only the missing lower bound needs to be added.

References

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