Security readout for executives and security teams
Plain-English summary
A flaw in the Linux MediaTek stateless HEVC video decoder can leave a freed pointer after decoder initialization fails. Later cleanup may use that pointer, causing a kernel crash and potentially compromising confidentiality, integrity, or availability. Exposure requires an affected kernel, the relevant MediaTek decoder path, and local access.
Executive priority
Treat as a high-priority local kernel issue on MediaTek video-decoding systems, especially shared or multi-user devices. Patch through supported vendor channels after confirming applicability; broad emergency action is not supported by the supplied exploitation evidence.
Technical view
The decoder stored its instance pointer before confirming successful HEVC initialization. If initialization failed, the instance was freed, but deinitialization could still dereference the stale pointer, producing a kernel use-after-free and oops. The fix stores the pointer only after successful initialization. The supplied CVSS is 7.8 with local, low-privilege attack requirements and no user interaction.
Likely exposure
Most relevant to Linux systems using the MediaTek stateless HEVC decoder. The supplied record identifies affected Linux versions but presents an ambiguous flattened version list, so exact distribution exposure cannot be determined from this bundle alone. Systems without the relevant driver or hardware path are less likely to be exposed.
Exploitation context
The supplied record does not identify CVE-2024-35921 as CISA KEV and provides no evidence of active exploitation or a public exploit. CVSS characterizes exploitation as local, low complexity, and requiring low privileges. Real-world exploitability beyond the documented kernel oops is not established by these sources.
Researcher notes
The demonstrated failure occurs during cleanup after HEVC initialization fails: deinitialization follows a stale instance pointer into vcodec_vpu_send_msg. The source supports a use-after-free and kernel oops, but does not establish reliable code execution. The Acer Tomato board is the reported test hardware, not proof that exposure is limited to that device.
Mitigation direction
- Obtain a vendor-supported kernel containing the referenced upstream or stable fix.
- Check distribution or device-vendor guidance for exact fixed package versions and backports.
- Prioritize systems exposing the MediaTek stateless HEVC decoder to untrusted local workloads.
- Consider vendor-approved restriction of the affected decoder path until updates are available.
Validation and detection
- Inventory kernels and devices that enable the MediaTek stateless HEVC decoder.
- Confirm the installed kernel includes a vendor backport or one of the referenced fixes.
- Review kernel logs for oops traces involving vcodec_vpu_send_msg and HEVC deinitialization.
- Use vendor advisories to resolve the source bundle's ambiguous affected-version entries.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CVE-2024-35921 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9LinuxVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/ec25fc3c2c1e8958a51abcfed614f81446d918c4CVE reference, Linux
- https://git.kernel.org/stable/c/521ce0ea7418298d754494fe53263c23c4c78a8eCVE reference, Linux
- https://git.kernel.org/stable/c/97c75ee5de060d271d80109b0c47cb6008439e5bCVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.