# CVE-2026-97620: drm/xe: Flush LSC untyped L1 dataport cache after rcs/ccs batches > Local attackers can read stale data from the GPU cache due to missing flushes, potentially leaking sensitive information from reclaimed memory. - **Severity:** Not scored - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 25 Sep 2026 - **Updated:** 19 Oct 2026 - **Also known as:** BELL-CVE-2026-97620, DEBIAN-CVE-2026-97620, GHSA-27vj-fv42-fgqc, UBUNTU-CVE-2026-97620 ## What is CVE-2026-97620? CVE-2026-97620 is a vulnerability in Linux, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: drm/xe: Flush LSC untyped L1 dataport cache after rcs/ccs batches emit_render_cache_flush() sets PIPE_CONTROL0_HDC_PIPELINE_FLUSH to flush the L2/HDC data cache before fence signalling, but it never requests a flush of the LSC untyped L1 data cache via the 'Untyped Data-Port Cache Flush Enable' bit in PIPE_CONTROL DWord0[11]. Per the Bspec, in 3D pipeline mode HDC Pipeline Flush is documented to also flush/invalidate the untyped L1 cache, but only depending on how HDC_CHICKEN0[13:11] is programmed. Starting with MTL, this coupling between HDC Pipeline Flush and the untyped L1 cache flush no longer holds in practice, regardless of how HDC_CHICKEN0 is programmed, so relying on it is not safe on newer platforms such as BMG. Mesa's Vulkan driver (anv) has been assuming the kernel flushes both caches between submissions, and hit user-visible corruption in apps such as Llama.cpp because of this gap; it now works around it by flushing both caches again from userspace at the end of every command buffer. Correctness between submissions on the same queue is userspace's responsibility and belongs in Mesa, not the kernel. However, for security we must ensure stale data can't leak through the untyped L1 dataport cache once memory is reclaimed or evicted, which requires the KMD to flush it before releasing memory for reuse. Prior to MTL, HDC_CHICKEN0 could be programmed (as already done for DG2 via Wa_22010960976/Wa_14013347512) to reliably keep HDC Pipeline Flush coupled to the untyped L1 cache flush, so those platforms are unaffected. Mesa's own anv driver found that on MTL the HW disconnected the two independently of how HDC_CHICKEN0 is programmed, and could not bring the old behavior back even by writing the register by hand; see Mesa commit 7c2ff46a4fc3 ("anv: don't prevent L1 untyped cache flush in 3D mode"). The kernel can't reliably request the flush from the CS on MTL either, so restrict the new PIPE_CONTROL bit to GRAPHICS_VERx100 >= 2000 (Xe2 and later), where it can be relied on. Explicitly set PIPE_CONTROL0_UNTYPED_DATAPORT_CACHE_FLUSH together with PIPE_CONTROL0_HDC_PIPELINE_FLUSH in emit_render_cache_flush() on Xe2 and later, so the L1 data cache is known clean before memory is released for reuse, without depending on undocumented platform-specific HDC_CHICKEN0 behavior. Bspec: 56551 (cherry picked from commit 434514b6fe731e873808297c268fc52cdf4a1ce6) ## Which versions are affected by CVE-2026-97620? ## How do I fix CVE-2026-97620? Apply the vendor's patch. ## Is CVE-2026-97620 being exploited? There is no known exploitation of CVE-2026-97620 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-97620 and fix it if it is affected. What it is: CVE-2026-97620 is a vulnerability in Linux, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-97620 in the wild and no public exploit code. Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-97620/ (Markdown: https://insights.sbomify.com/CVE-2026-97620/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97620 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97620 - OSV: https://osv.dev/vulnerability/CVE-2026-97620 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-97620/ Summaries are generated and may contain mistakes; the official description above is the record.