# CVE-2021-38202: Linux Kernel out-of-bounds read in nfsd tracepoint

Source: https://junglewise.ai/threats/cve-2021-38202-linux-kernel-out-of-bounds-read-in-nfsd-tracepoint  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-08-08. Updated: 2026-05-12  
License: CC BY 4.0 with a link back

CVE-2021-38202 · Severity: high · CVSS 7.5 · Published 2021-08-08

A vulnerability in the Linux kernel's Network File System (NFS) server component could allow a remote attacker to crash the system. This occurs when specific diagnostic tracing features are enabled and the system receives specially crafted network traffic. An exploit would result in a denial of service, potentially disrupting business operations and data availability.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel), [NetApp Hci Bootstrap Os](https://junglewise.ai/threats/technologies/hci-bootstrap-os), [NetApp Hci Compute Node](https://junglewise.ai/threats/technologies/hci-compute-node), [Siemens SIMATIC S7-1500 TM MFP](https://junglewise.ai/threats/technologies/simatic-s7-1500-tm-mfp). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux), [NetApp](https://junglewise.ai/threats/vendors/netapp), [Siemens](https://junglewise.ai/threats/vendors/siemens).

## Quick answers

**Is CVE-2021-38202 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-38202 being exploited in the wild.

**How severe is CVE-2021-38202?** High severity, with a CVSS score of 7.5, published 8 August 2021.

**Which products and versions are affected?** Siemens SIMATIC S7-1500 TM MFP All versions using GNU/Linux subsystem.

**Is there a fix for CVE-2021-38202?** A patch was published on 2021-07-20: Fixed in Linux kernel version 5.13.4 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2021-38202 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2021-38202?** Check whether you run Linux Kernel, NetApp Element Software, NetApp Hci Bootstrap Os or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds read vulnerability exists in fs/nfsd/trace.h within the Linux kernel's NFS server (nfsd) implementation. The issue stems from the nfsd_dirent tracepoint using __assign_str(), which internally calls strlen() on a string that is not guaranteed to be NUL-terminated. A remote attacker can trigger this by sending specific NFS traffic while the trace event framework is active for nfsd. This leads to a kernel oops or system crash (Denial of Service). The vulnerability was fixed in Linux kernel version 5.13.4 by removing the redundant and unsafe __assign_str() call.

## Affected products

- Linux Linux Kernel before 5.13.4
- Siemens SIMATIC S7-1500 TM MFP All versions using GNU/Linux subsystem
- NetApp Element Software -
- NetApp HCI Storage Node -

## Timeline

- 2021-07-20: patched: Fixed in Linux kernel version 5.13.4
- 2021-08-08: disclosed: NVD publication date
- 2024-04-09: advisory: Siemens published advisory SSA-265688 covering this CVE

## References

- [https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4](https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4)
- [https://github.com/torvalds/linux/commit/7b08cf62b1239a4322427d677ea9363f0ab677c6](https://github.com/torvalds/linux/commit/7b08cf62b1239a4322427d677ea9363f0ab677c6)
- [https://security.netapp.com/advisory/ntap-20210902-0010/](https://security.netapp.com/advisory/ntap-20210902-0010/)
- [https://cert-portal.siemens.com/productcert/html/ssa-265688.html](https://cert-portal.siemens.com/productcert/html/ssa-265688.html)

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