Medium [CVE-2026-68287] Linux kernel: Denial of Service in drop_monitor due to incorrect size calculations
This medium-severity Red Hat Linux advisory covers CVE-2026-68287 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux for NVIDIA 26.
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Summary
In the Linux kernel, the following vulnerability has been resolved: drop_monitor: fix size calculations for 64-bit attributes net_dm_packet_report_fill() and net_dm_hw_packet_report_fill() use nla_put_u64_64bit() to append 64-bit attributes (NET_DM_ATTR_PC and NET_DM_ATTR_TIMESTAMP).
On 32-bit architectures without CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, nla_put_u64_64bit() may append a 4-byte NET_DM_ATTR_PAD attribute for 64-bit alignment. However, net_dm_packet_report_size() and net_dm_hw_packet_report_size() used nla_total_size(sizeof(u64)) instead of nla_total_size_64bit(sizeof(u64)), budgeting 12 bytes instead of up to 16 bytes.
This under-estimation of SKB size can lead to an skb_over_panic() when __nla_reserve() or skb_put() is subsequently called. Fix this by using nla_total_size_64bit(sizeof(u64)) in both size calculations.
Incorrect size calculations for 64-bit attributes on 32-bit architectures without efficient unaligned access support can lead to an under-estimation of internal buffer (SKB) size. This under-estimation may cause a kernel panic, resulting in a Denial of Service (DoS) for the affected system.
Red Hat severity: Important — CVSS 4.1 (CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-787.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux for NVIDIA 26.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
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