CVE-2024-21626 — runc container breakout through process.cwd trickery and leaked fds

Description (CNA)

runc is a CLI tool for spawning and running containers on Linux according to the OCI specification. In runc 1.1.11 and earlier, due to an internal file descriptor leak, an attacker could cause a newly-spawned container process (from runc exec) to have a working directory in the host filesystem namespace, allowing for a container escape by giving access to the host filesystem ("attack 2"). The same attack could be used by a malicious image to allow a container process to gain access to the host filesystem through runc run ("attack 1"). Variants of attacks 1 and 2 could be also be used to overwrite semi-arbitrary host binaries, allowing for complete container escapes ("attack 3a" and "attack 3b"). runc 1.1.12 includes patches for this issue.

Affected (CNA)

Vendor / product	Versions
opencontainers / runc	affected >=v1.0.0-rc93, < 1.1.12

CWE

CWE-403, CWE-668

References

ADP enrichment

CVE

No English description supplied.

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A file descriptor leak issue was found in the runc package. While a user performs `O_CLOEXEC` all file descriptors before executing the container code, the file descriptor is open when performing `setcwd(2)`, which means that the reference can be kept alive in the container by configuring the working directory to be a path resolved through the file descriptor. The non-dumpable bit is unset after `execve`, meaning there are multiple ways to attack this other than bad configurations. The only way to defend against it entirely is to close all unneeded file descriptors.