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Advisory severityHigh7.0Vendor: MediumRed Hat Linux

High [CVE-2026-53223] guard timestamp cmsgs to real error queue skbs

This high-severity Red Hat Linux advisory covers CVE-2026-53223 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-53223 Source published Source updated

VulniPulse record published Record updated

CVE-2026-53223
Affected products & platforms
Red Hat LinuxLinux Kernel
Open source advisory

Summary

In the Linux kernel, the following vulnerability has been resolved: net: guard timestamp cmsgs to real error queue skbs skb_is_err_queue() treats PACKET_OUTGOING as the sole marker for an skb from sk_error_queue.

That assumption is not true for AF_PACKET sockets: outgoing packet taps are also delivered to packet sockets with skb->pkt_type == PACKET_OUTGOING, but their skb->cb is owned by AF_PACKET instead of struct sock_exterr_skb.

If such an skb is received with timestamping enabled, the generic timestamp cmsg path can read AF_PACKET control-buffer state as sock_exterr_skb::opt_stats. With SO_RXQ_OVFL enabled, the packet drop counter overlaps opt_stats.

An odd drop count makes the path emit SCM_TIMESTAMPING_OPT_STATS with skb->len and skb->data. For non-linear skbs this copies past the linear head and can trigger hardened usercopy or disclose adjacent heap contents.

Keep skb_is_err_queue() local to net/socket.c, but make it verify that the PACKET_OUTGOING marker is paired with the sock_rmem_free destructor installed by sock_queue_err_skb().

AF_PACKET receive skbs use normal receive ownership and no longer pass as error-queue skbs, while legitimate sk_error_queue entries keep the PACKET_OUTGOING marker and sock_rmem_free ownership. A flaw was found in the Linux kernel's networking component.

Is CVE-2026-53223 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-53223 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-53223?

Upgrade to a fixed release named by Red Hat:

  • kernel-0:6.12.0-211.52.1.el10_2
  • kernel-rt-0:4.18.0-553.164.1.rt7.505.el8_10
  • kernel-0:4.18.0-553.164.1.el8_10
  • kernel-0:5.14.0-687.46.1.el9_8
  • RHSA-2026:64775
  • RHSA-2026:68532
  • RHSA-2026:68531
  • RHSA-2026:66180

Confirm against the vendor advisory before you patch.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

Fixed versions
  • kernel-0:6.12.0-211.52.1.el10_2
  • kernel-rt-0:4.18.0-553.164.1.rt7.505.el8_10
  • kernel-0:4.18.0-553.164.1.el8_10
  • kernel-0:5.14.0-687.46.1.el9_8
  • RHSA-2026:64775
  • RHSA-2026:68532
  • RHSA-2026:68531
  • RHSA-2026:66180

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

Mitigation

Upgrade to a fixed release: kernel-0:6.12.0-211.52.1.el10_2, kernel-rt-0:4.18.0-553.164.1.rt7.505.el8_10, kernel-0:4.18.0-553.164.1.el8_10, kernel-0:5.14.0-687.46.1.el9_8, RHSA-2026:64775, RHSA-2026:68532. That is the remediation for this advisory.

The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

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