CVE-2024-57924 Cert Portal CVE debrief

Who should care

Administrators and security teams responsible for Linux kernels or vendor products that embed affected kernel components, especially systems where local users are present or where kernel availability and stability are operationally important. The Siemens-mapped advisory in the supplied corpus should be checked carefully before assuming direct product exposure.

Technical summary

The vulnerable code path involves exportfs_encode_fh() / exportfs_encode_fid() handling of filesystem file-handle encoding failures. Some callers treated ->encode_fh() failure as an assertion condition and used WARN_ON(), even though encode_fh() may fail for normal filesystem-specific reasons. The upstream change removes or relaxes those assertions because the failure is expected in some cases. The advisory also notes that a referenced overlayfs commit increased the chances of triggering the warning, but was not the underlying root cause and is not listed as a Fixes commit.

Defensive priority

Medium. The corpus rates the issue CVSS 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), indicating local attacker prerequisites but potentially significant availability impact. Prioritize if the affected kernel runs on shared, multi-user, or high-availability systems.

Recommended defensive actions

• Apply the vendor or distribution update that includes the assertion-relaxation fix.
• If you are tracking the Siemens-mapped advisory in the supplied corpus, follow the stated remediation to update to V5.0 or later where applicable.
• Review kernel/package versions on exposed systems and confirm whether the fix has been backported into your stable branch.
• Monitor for repeated kernel WARN_ON messages related to exportfs or file-handle encoding and treat them as a sign that the affected path needs updating.
• Restrict unnecessary local access on systems where local users are not required, since the CVSS vector in the corpus requires local access.

Evidence notes

The supplied source item is CISA CSAF publication ICSA-26-134-10, republished from Siemens ProductCERT advisory SSA-032379. The corpus publication date is 2026-05-12 and the modified/republication date is 2026-05-14. The advisory text states that legacy users of exportfs_encode_fh(), including nfsd and name_to_handle_at(2), are already prepared for failure, and that the WARN_ON assertions in other callers are wrong. The corpus also says commit 16aac5ad1fa9 increased the chance of triggering the warning but was not the true regression root. CVSS in the corpus is 5.5 with vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Official resources