Local crash or hang via misaligned fence
Published Aug 10, 2026 · Updated Aug 10, 2026
Reachable assertion in Linux before 7.1.6 allows local users to crash or hang systems through an unaligned AMDGPU SDMA fence address. The sdma_v7_1_ring_emit_fence() callback applies fatal BUG_ON(addr & 0x3) assertions to the user-controlled fence writeback address instead of rejecting a misaligned offset at the ioctl boundary. Reachability requires local access to an AMDGPU render node and SDMA 7.1; in 7.1 and later, the nondefault amdgpu.user_queue=0 setting reopens the path.
Summary
What happened
Reachable assertion in Linux before 7.1.6 allows local users to crash or hang systems through an unaligned AMDGPU SDMA fence address. The sdma_v7_1_ring_emit_fence() callback applies fatal BUG_ON(addr & 0x3) assertions to the user-controlled fence writeback address instead of rejecting a misaligned offset at the ioctl boundary. Reachability requires local access to an AMDGPU render node and SDMA 7.1; in 7.1 and later, the nondefault amdgpu.user_queue=0 setting reopens the path.
The record
- CVE
- CVE-2026-68109
- Published
- Aug 10, 2026
- Updated
- Aug 10, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-617, T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 10, 2026CVE publishedPublication date reported by the CVE source.
- Aug 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <7.1.6
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <253b1401862b9eb2be54f63546505a40a14672dd
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <767648c18d7872bbf54481ba846e055f7e1c0213
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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