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Vulnerability record · CVE-2026-53223 · published 25 June 2026

CVE-2026-53223: Linux kernel vulnerability

Linux · Linux Kernel

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.

7.1 CVSS 3.1 High EPSS 0.13% · top 97.9%
7.1CVSS 3.1 base score
0.13%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
9References
8 Sep 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/1ee90b77b727df903033db873c75caac5c27ec98 Patch
https://git.kernel.org/stable/c/24a0d548d3a765cd4558224e4f8e06e14cba26e3 Patch
https://git.kernel.org/stable/c/3dde4fb941fa5649ab809f6cd3e20e0c424a4e31 Patch
https://git.kernel.org/stable/c/71ff5cdd5da61d0438e902aa0fd68c28bc901abe Patch
https://git.kernel.org/stable/c/ad9a0374ee6d11048e1f74cd5180bad58b9848b4 Patch
https://git.kernel.org/stable/c/b903e9b5629ec8dd6db92174070045bf81ad7060 Patch
https://git.kernel.org/stable/c/e0665b2a8e90bb08bd205062c75662b502d31797 Patch
https://git.kernel.org/stable/c/eb51a9ad3ceb01bc6c0fb608dbc856e03ee6f24a Patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html

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Source: NIST National Vulnerability Database (record CVE-2026-53223), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.