High [CVE-2026-53136] Clamp VBIOS HDMI retimer register count to array size
This high-severity Red Hat Linux advisory covers CVE-2026-53136 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Clamp VBIOS HDMI retimer register count to array size [Why & How] The VBIOS integrated info tables (v1_11 and v2_1) contain HdmiRegNum and Hdmi6GRegNum fields that are used as loop bounds when copying retimer I2C register settings into fixed-size arrays (dp*_ext_hdmi_reg_settings[9] and dp*_ext_hdmi_6g_reg_settings[3]).
These u8 fields are not validated before use, so a malformed VBIOS can specify values up to 255, causing an out-of-bounds heap write during driver probe.
Clamp each register count to the destination array size using min_t() before the copy loops, in both get_integrated_info_v11() and get_integrated_info_v2_1(). (cherry picked from commit 5a7f0ef90195940c54b0f5bb85b87da55f038c69) This vulnerability occurs when the driver processes malformed VBIOS (Video Basic Input/Output System) data.
Specifically, unvalidated register counts in the VBIOS can lead to an out-of-bounds memory write during the driver's initialization. This memory corruption could allow an attacker with local access to potentially cause a system crash (denial of service) or execute arbitrary code.
Red Hat severity: Important — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-1284.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
- kernel-0:6.12.0-211.49.1.el10_2
- kernel-rt-0:4.18.0-553.156.1.rt7.497.el8_10
- kernel-0:4.18.0-553.156.1.el8_10
- kernel-0:5.14.0-687.41.1.el9_8
- RHSA-2026:57251
- RHSA-2026:55765
- RHSA-2026:55764
- RHSA-2026:57252
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation
Upgrade to a fixed release: kernel-0:6.12.0-211.49.1.el10_2, kernel-rt-0:4.18.0-553.156.1.rt7.497.el8_10, kernel-0:4.18.0-553.156.1.el8_10, kernel-0:5.14.0-687.41.1.el9_8, RHSA-2026:57251, RHSA-2026:55765. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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