CVE-2022-50753: 
Linux Debian vulnerability analysis and mitigation

CVE-2022-50753 is a use-after-free vulnerability in the Linux kernel's F2FS (Flash-Friendly File System) subsystem, triggered by a corrupted SSA (Summary Store Area) table during filesystem recovery or garbage collection. When mounting a crafted or fuzzed F2FS image, the ofs_in_node field in the SSA table can exceed ADDRS_PER_PAGE(), causing an out-of-range memory access detected by KASAN. The vulnerability affects Linux kernel versions from the initial F2FS introduction up to (but not including) the patched stable releases: 5.4.220, 5.10.150, 5.15.75, 5.19.17, 6.0.3, and 6.1. It was published on December 24, 2025, with a CVSS category estimate of Medium and an EPSS score of 0.000240 (Red Hat CVE, Feedly).

The root cause is insufficient input validation on F2FS summary information (CWE-125: Out-of-bounds Read / use-after-free, CWE-416). During recover_data → do_recover_data → check_index_in_prev_nodes → f2fs_data_blkaddr, the kernel reads ofs_in_node from the SSA table without verifying it is within bounds of ADDRS_PER_PAGE() for a 4KB page. A specially crafted or fuzzed F2FS image with a corrupted SSA table can set ofs_in_node to a value such as 65286 (far exceeding the valid maximum of 1018), triggering an out-of-range read and a KASAN use-after-free report. The fix adds a sanity check on summary info in both the recovery and garbage collection (GC) code paths (Red Hat CVE, ENISA/EUVD).

Successful exploitation can cause system instability, kernel crashes (denial of service), or unauthorized out-of-bounds memory reads during the filesystem mount process. The vulnerability is triggered locally when a privileged or unprivileged user (depending on system configuration) mounts a malicious F2FS image, potentially exposing kernel memory contents or causing a system crash. There is no evidence of remote exploitability or lateral movement potential; the primary risk is availability impact and potential information disclosure from kernel memory (Feedly).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation as of the publication date. The vulnerability was originally reported via the Linux kernel bugzilla (bug #216456) by Wenqing Liu using a fuzzed F2FS image. The EPSS score is 0.000240, indicating very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog (Feedly, Red Hat Bugzilla).

Update to a patched Linux kernel version: 5.4.220, 5.10.150, 5.15.75, 5.19.17, 6.0.3, or 6.1 (or later). As a workaround, avoid mounting F2FS filesystems from untrusted or unknown sources, and restrict the ability of unprivileged users to mount filesystems (e.g., via nosuid/nodev mount policies or disabling user-namespace-based mounts). Kernel patches are available in the stable tree for all affected branches (Red Hat CVE, Red Hat Bugzilla).