CVE-2026-68277 drm/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers
Out-of-bounds reads in Linux kernel DisplayPort MST sideband parsers allow attackers to read adjacent memory or cause crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68277?
CVE-2026-68277 is a memory corruption vulnerability in Linux, published on 10 Aug 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/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers
Three sideband reply parsers read 16-bit fields as:
val = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
and check bounds only after the fact. When idx == raw->curlen, raw->msg[idx+1] reads one byte past the received message data into the following struct fields (curchunk_len, curchunk_idx, curlen).
Affected functions: - drm_dp_sideband_parse_enum_path_resources_ack() full_payload_bw_number and avail_payload_bw_number fields - drm_dp_sideband_parse_allocate_payload_ack() allocated_pbn field - drm_dp_sideband_parse_query_payload_ack() allocated_pbn field
Fix by using a single combined check (idx + 2 > curlen) before each 2-byte read. Since the check is strictly tighter than idx > curlen, no separate step is needed.
[added fixes tag]
Which versions are affected by CVE-2026-68277?
How do I fix CVE-2026-68277?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-68277 being exploited?
There is no known exploitation of CVE-2026-68277 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68277, DEBIAN-CVE-2026-68277, GHSA-5g47-cvq4-4x2c, UBUNTU-CVE-2026-68277.