--- id: CVE-2026-68278 title: |- In the Linux kernel, the following vulnerability has been resolved: drm/dp/mst: fix buffer overflows in sideband chunk accumulation drm_dp_sideband_append_payload() has three related bugs when processing device-provided sideband reply … summary: |- In the Linux kernel, the following vulnerability has been resolved: drm/dp/mst: fix buffer overflows in sideband chunk accumulation drm_dp_sideband_append_payload() has three related bugs when processing device-provided sideband reply … severity: high published: '2026-08-10' updated: '2026-08-23' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-68278' references: - url: 'https://git.kernel.org/stable/c/1e5827839ad0ceb0079d1560c321fa3656b54f21' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/4d5109075a787de28c9e89940f9dee45269f91fa' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/53937a2787d29c7a460e984dc4f20ff6ac91dc65' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/55bd5e685bda455b9b50c835f8c8442d52a344a3' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/a6366b551079c79bf7bdbadd74c97358bcfe2d58' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/d4e05dedb252ed3e540a0c9be511e427f098110a' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/ef0dbcc200c3389f1f781ab181932a97e54b51af' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/ef2ecb6cf268debf3890df99fea01b6452dcf78e' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68278.json - url: 'https://access.redhat.com/security/cve/CVE-2026-68278' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2513287' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-68278' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-68278' - url: >- https://lore.kernel.org/linux-cve-announce/2026081025-CVE-2026-68278-ddb6@gregkh/T - url: 'https://access.redhat.com/errata/RHSA-2026:81552' - url: 'https://access.redhat.com/errata/RHSA-2026:82806' - url: 'https://access.redhat.com/errata/RHSA-2026:82807' - url: 'https://access.redhat.com/errata/RHSA-2026:88477' tags: - nvd - csaf - vex - red-hat epss: 0.00238 epssPercentile: 0.14743 ingestedAt: '2026-08-23T13:48:06.902Z' vendor: Red Hat product: Red Hat Enterprise Linux 9 affected: - enterprise_linux 10 - enterprise_linux 8 - enterprise_linux 9 cvss: 7.3 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H' cvssSource: vendor cwe: - CWE-120 patched: - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_nfv_v_8 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_rt_v_8 - enterprise_linux_real_time_v_9 --- ## Overview In the Linux kernel, the following vulnerability has been resolved: drm/dp/mst: fix buffer overflows in sideband chunk accumulation drm_dp_sideband_append_payload() has three related bugs when processing device-provided sideband reply data: 1. Zero-length curchunk_len underflow: msg_len is a 6-bit field taken directly from the DP sideband header. If a device sends msg_len=0, curchunk_len is set to zero. The condition (curchunk_idx >= curchunk_len) is immediately true, and curchunk_len-1 wraps to 255 (u8 underflow). drm_dp_msg_data_crc4() reads 255 bytes from chunk[48], then memcpy() writes 255 bytes into msg[], both far out of bounds. 2. chunk[48] overflow: curchunk_len can reach 63 (6-bit field). chunk[] is only 48 bytes. Multi-iteration payload assembly appends 16-byte blocks until curchunk_idx reaches curchunk_len, writing up to 15 bytes past the end of chunk[] into msg[]. 3. msg[256] overflow: each chunk contributes (curchunk_len-1) bytes to msg[]. No check ensures curlen + (curchunk_len-1) stays within msg[256], so the memcpy can spill into adjacent struct fields. All three are reachable from any DP MST device that can forge sideband reply messages on a physical connection. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 9 · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68278.json) - **RHSA-2026:81552** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9), Red Hat Enterprise Linux Real Time (v. 9) · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:81552) - **RHSA-2026:82806** · Red Hat · fixed in: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8) · released 2026-10-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:82806) - **RHSA-2026:82807** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-10-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:82807) - **RHSA-2026:88477** · Red Hat · fixed in: 10Base-SMTV, Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Hidden (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10), … · released 2026-10-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:88477)