CVE-2023-53825
kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg().
Description
In the Linux kernel, the following vulnerability has been resolved: kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg(). syzkaller found a memory leak in kcm_sendmsg(), and commit c821a88bd720 ("kcm: Fix memory leak in error path of kcm_sendmsg()") suppressed it by updating kcm_tx_msg(head)->last_skb if partial data is copied so that the following sendmsg() will resume from the skb. However, we cannot know how many bytes were copied when we get the error. Thus, we could mess up the MSG_MORE queue. When kcm_sendmsg() fails for SOCK_DGRAM, we should purge the queue as we do so for UDP by udp_flush_pending_frames(). Even without this change, when the error occurred, the following sendmsg() resumed from a wrong skb and the queue was messed up. However, we have yet to get such a report, and only syzkaller stumbled on it. So, this can be changed safely. Note this does not change SOCK_SEQPACKET behaviour.
INFO
Published Date :
Dec. 9, 2025, 4:17 p.m.
Last Modified :
Dec. 9, 2025, 6:37 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Update the Linux kernel to the patched version.
- Verify the fix resolves the memory leak.
- Test DGRAM socket operations after update.
References to Advisories, Solutions, and Tools
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CVE-2023-53825.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2023-53825 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
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stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2023-53825
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).
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CVE-2023-53825 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2023-53825 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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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Dec. 09, 2025
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg(). syzkaller found a memory leak in kcm_sendmsg(), and commit c821a88bd720 ("kcm: Fix memory leak in error path of kcm_sendmsg()") suppressed it by updating kcm_tx_msg(head)->last_skb if partial data is copied so that the following sendmsg() will resume from the skb. However, we cannot know how many bytes were copied when we get the error. Thus, we could mess up the MSG_MORE queue. When kcm_sendmsg() fails for SOCK_DGRAM, we should purge the queue as we do so for UDP by udp_flush_pending_frames(). Even without this change, when the error occurred, the following sendmsg() resumed from a wrong skb and the queue was messed up. However, we have yet to get such a report, and only syzkaller stumbled on it. So, this can be changed safely. Note this does not change SOCK_SEQPACKET behaviour. Added Reference https://git.kernel.org/stable/c/1ce8362b4ac6b8e65fd04a22ea37ec776ee1ec5b Added Reference https://git.kernel.org/stable/c/21b467735b0888a8daa048f83d3b9b50fdab71ce Added Reference https://git.kernel.org/stable/c/2e18493c421428a936946c452461b8e979088f17 Added Reference https://git.kernel.org/stable/c/55d2e7c1ab8eaa7b62575b8a4194132795d1f9fc Added Reference https://git.kernel.org/stable/c/992b2ac783aad360b98ed9d4686e86176a20f6f1 Added Reference https://git.kernel.org/stable/c/a22730b1b4bf437c6bbfdeff5feddf54be4aeada Added Reference https://git.kernel.org/stable/c/d4b8f380b0a041ee6a84fdac14127d8fe1dcad7b Added Reference https://git.kernel.org/stable/c/e5b28ce127a690f3acc49a6a342e6c9442c9edd6