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CVE Record

CVE-2023-53825: kcm: Fix error handling for SOCK_DGRAM in kcm_sendmsg().

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2023-53825 is a Linux kernel KCM networking bug found by syzkaller. The issue affects error handling for SOCK_DGRAM sends and can leave queued message state incorrect. Public sources do not provide CVSS, CWE, severity, or evidence of real-world exploitation.

Executive priority

Treat this as a kernel maintenance and exposure-tracking item, not an emergency based on current evidence. Prioritize normal patch cycles unless your environment relies on KCM, runs untrusted workloads, or a vendor later assigns higher severity.

Technical view

In kcm_sendmsg(), a prior memory-leak fix updated last_skb after partial copy. For SOCK_DGRAM errors, the kernel cannot know copied byte counts, so MSG_MORE queue state can become inconsistent. The resolved behavior purges the queue, similar to UDP. Sources state SOCK_SEQPACKET behavior is unchanged.

Likely exposure

Exposure appears limited to Linux systems running affected kernel code paths using KCM SOCK_DGRAM sockets. The source bundle lists Linux kernel versions and stable commits but does not clarify distribution-specific package impact, default module availability, or required privileges.

Exploitation context

The source states syzkaller found the issue and that no related report had been received. KEV is false, and the provided sources do not claim active exploitation, public exploit availability, or weaponized use.

Researcher notes

The key behavior is SOCK_DGRAM error-path cleanup in KCM. The fix purges pending frames because copied-byte accounting is unreliable after an error. Evidence is strongest for correctness and memory/queue handling, while security impact remains insufficiently characterized in the bundle.

Mitigation direction

  • Check Linux distribution advisories for CVE-2023-53825 package status.
  • Update affected systems to vendor-supported kernels containing the referenced stable fixes.
  • Prioritize internet-facing multi-tenant or untrusted workload hosts for kernel review.
  • If patching is delayed, assess whether KCM is used or needed.
  • Do not assume source version strings map directly to distro packages.

Validation and detection

  • Inventory running kernel versions across Linux hosts.
  • Map vendor kernel packages to the referenced stable commits or advisories.
  • Review whether KCM-related functionality is enabled or used in critical environments.
  • Confirm patched kernels are booted, not merely installed.
  • Monitor vendor advisories for severity or exploitability updates.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2023-53825 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
9Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxab7ac4eb9832e32a09f4e8042705484d2fb0aad3, ab7ac4eb9832e32a09f4e8042705484d2fb0aad3, ab7ac4eb9832e32a09f4e8042705484d2fb0aad3, ab7ac4eb9832e32a09f4e8042705484d2fb0aad3, ab7ac4eb9832e32a09f4e8042705484d2fb0aad3, ab7ac4eb9832e32a09f4e8042705484d2fb0aad3, ab7ac4eb9832e32a09f4e8042705484d2fb0aad3, ab7ac4eb9832e32a09f4e8042705484d2fb0aad3unaffected
LinuxLinux4.6, 0, 4.14.326, 4.19.295, 5.4.257, 5.10.195, 5.15.132, 6.1.54, 6.5.4, 6.6affected
Weakness

CWE details

No CWE listed

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