CVE-2024-53146

What it actually does

Integer overflow in NFSD decode_cb_compound4res when tag length >= U32_MAX - 3 during addition of length + 4, addressed by splitting unsafe length arithmetic into multiple decode steps.

Why it matters to the business

Potential denial-of-service or memory corruption in NFS servers could disrupt file-sharing services across Linux environments; low exploit likelihood and no known ransomware use reduce immediate operational risk despite broad kernel prevalence.

How an attack unfolds

An attacker supplies a crafted NFSv4 compound response containing an oversized tag length to trigger the unchecked addition inside decode_cb_compound4res, causing wrap-around that may lead to invalid memory access or kernel instability.

How to fix it

Apply the upstream fix in commit 745f7ce5a95e783ba62fe774325829466aec2aa8 or later; for Ubuntu 14.04 LTS upgrade squid3 to 3.3.8-1ubuntu6.8; for Ubuntu 16.04 LTS upgrade squid3 to 3.5.12-1ubuntu7.2; rebuild and reboot affected kernels.

How to confirm the fix worked

Confirm kernel source contains the multi-step decode logic or verify running kernel version includes commit 745f7ce5a95e; test NFS compound decoding with boundary tag lengths.

Typical attack path

1. Identify reachable NFS server exposing NFSD
2. Craft compound response with tag length near U32_MAX
3. Send malicious packet triggering length + 4 overflow
4. Observe resulting kernel panic or undefined behavior

How to detect it

Review kernel logs for NFSD decode errors or oops messages around compound response handling; correlate with unusual NFSv4 traffic volumes from untrusted sources.

What your security team should do

• Prioritize kernel and NFS package upgrades on all exposed systems within standard change windows
• Monitor EPSS and threat intelligence for any rise in exploitation attempts
• Restrict NFS exposure to trusted networks until patches are deployed