EUVD-2026-38707
GHSA-2xmc-f6qc-h4h9
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Local access and low privileges to open macvtap device required; impact is purely confidentiality (kernel pointer disclosure), no integrity or availability consequence.
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
5DescriptionNVD
In the Linux kernel, the following vulnerability has been resolved:
tap: fix stack info leak in tap_ioctl() SIOCGIFHWADDR
In the SIOCGIFHWADDR path, tap_ioctl() copies 16 bytes of an uninitialised on-stack struct sockaddr_storage to userspace via ifr_hwaddr, but netif_get_mac_address() only writes sa_family and dev->addr_len (6 for Ethernet) bytes, leaving sa_data[6..13] uninitialised.
Those 8 trailing bytes leak kernel stack contents; SIOCGIFHWADDR on a macvtap chardev returns kernel .text and direct-map pointers, defeating KASLR.
Initialise ss at declaration.
AnalysisAI
Stack information disclosure in the Linux kernel's tap/macvtap driver exposes 8 bytes of uninitialized kernel stack contents to local users via the SIOCGIFHWADDR ioctl, leaking kernel .text and direct-map pointers that defeat KASLR. The affected code path in tap_ioctl() copies a 16-byte sockaddr_storage to userspace while netif_get_mac_address() initializes only 8 bytes (sa_family plus 6-byte Ethernet address), leaving the trailing 8 bytes unread. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a local attacker with low-privilege access to a macvtap or tap character device (e.g., /dev/tapX). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The real-world risk of this vulnerability is moderate-to-significant despite the misleading CVSS vector provided with the advisory. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A local user or malicious process running inside a virtual machine whose NIC is backed by a host macvtap device opens /dev/tapX and issues ioctl(fd, SIOCGIFHWADDR, &ifr). The returned ifr_hwaddr contains the expected MAC address in the first 8 bytes, but bytes 8-15 hold uninitialized kernel stack data from a previous stack frame - including kernel .text addresses and physmap pointers. … |
| Remediation | The primary fix is to upgrade to a patched Linux kernel version: 7.1 or later, 7.0.11 or later in the 7.0.x stable series, or 6.18.34 or later in the 6.18.x stable series, per EUVD patch metadata. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-401 – Memory Leak
View allSame technique Information Disclosure
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External POC / Exploit Code
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