Podman seccomp AF_VSOCK/NETLINK_AUDIT bypass via 64-bit int truncation
CVE-2026-123876 Published on November 6, 2026
Podman: containers-common: containers-common: default seccomp af_vsock/netlink_audit deny rules bypassable via 32-bit truncation
A flaw was found in the default seccomp profile used by Podman via containers-common. Deny rules for AF_VSOCK and NETLINK_AUDIT compared socket arguments with unmasked 64-bit equality. Because the kernel truncates those int arguments to 32 bits, setting upper bits can bypass the deny rules.
Vulnerability Analysis
CVE-2026-123876 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Timeline
Reported to Red Hat.
Made public.
Weakness Type
What is a Denylist / Deny List Vulnerability?
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. Developers often try to protect their products against malicious input by performing tests against inputs that are known to be bad, such as special characters that can invoke new commands. However, such lists often only account for the most well-known bad inputs. Attackers may be able to find other malicious inputs that were not expected by the developer, allowing them to bypass the intended protection mechanism.
CVE-2026-123876 has been classified to as a Denylist / Deny List vulnerability or weakness.
Products Associated with CVE-2026-123876
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