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PatchSiren cyber security CVE debrief

CVE-2026-74582 Linux CVE debrief

The Linux kernel has a vulnerability in the packet send paths. packet_snd() and packet_sendmsg_spkt() do not consistently use the device's hard_header_len, which can lead to out-of-bounds writes. This issue arises because packet_snd() reads dev->hard_header_len multiple times while allocating and constructing an skb, and device reconfiguration can change this value concurrently. For SOCK_RAW, packet_snd() can save a larger value in reserve and later allocate headroom using a smaller value. Moving skb->data back by reserve then places it before skb->head, and the following copy from userspace can attempt an out-of-bounds write. packet_sendmsg_spkt() has the same issue because it calculates its reservation and header offset from separate reads before dropping the RCU read lock to allocate the skb. To address this, add LL_RESERVED_SPACE_EX() for callers that already saved a header length. Read hard_header_len once in packet_snd() and use it for allocation and construction. In packet_sendmsg_spkt(), preserve the allocation-time value through the device lookup retry. The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here. This vulnerability can be exploited by an attacker to potentially execute arbitrary code or cause a denial of service. Linux kernel developers, administrators, and security teams should be aware of this vulnerability and take necessary actions to mitigate it.

Vendor
Linux
Product
Unknown
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-21
Original CVE updated
2026-08-21
Advisory published
2026-08-21
Advisory updated
2026-08-21

Who should care

Linux kernel developers, administrators, and security teams should be aware of this vulnerability and take necessary actions to mitigate it. Affected product deployments should be identified, and owners should be assigned for follow-up. Compensating controls should be reviewed for exposed systems while remediation is scheduled and verified. Relevant monitoring, detection, and logs should be checked for exposed assets that need extra review. Exceptions should be tracked, and remediated assets should be retested and closed only after evidence is documented.

Technical summary

The Linux kernel has a vulnerability in the packet send paths. packet_snd() and packet_sendmsg_spkt() do not consistently use the device's hard_header_len, which can lead to out-of-bounds writes. This issue can be exploited by an attacker to potentially execute arbitrary code or cause a denial of service. The vulnerability is caused by the inconsistent use of hard_header_len in packet_snd() and packet_sendmsg_spkt(), which can lead to out-of-bounds writes. To mitigate this vulnerability, it is recommended to review and apply the provided kernel patches, monitor network traffic for suspicious activity, and consider implementing additional security controls.

Defensive priority

Medium

Recommended defensive actions

  • Review and apply the provided kernel patches
  • Monitor network traffic for suspicious activity
  • Consider implementing additional security controls
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide limited information about the vulnerability. Further analysis is needed to fully understand the issue. The Linux kernel packet send paths vulnerability (CVE-2026-74582) has been identified, but details on affected products, versions, and potential exploits are not explicitly stated. Defenders should verify the vulnerability's impact on their systems, review the provided kernel patches, and consider implementing additional security controls. Evidence is limited, and careful review of the CVE record, NVD entry, and related sources is necessary.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-08-21T17:16:44.507Z and has not been modified since then.