CVE-2021-38199 — fs/nfs/nfs4client.c in the Linux kernel before 5.13.4 has incorrect connection-setup ordering,...

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

• Documented patch — cdn.kernel.org (NIST National Vulnerability Database)
• Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Debian Debian Linux, Linux Linux Kernel, Netapp Element Software…).
2. Apply the fixed version or the patch documented under Remediation.
3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.25%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Not enough vector or weakness data: use the affected application’s logs as a starting point.

Timeline

What happened to this CVE, newest first.

• 2026
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Record published
  Oct 13, 2026
• Fix documented
  Oct 13, 2026 · NIST National Vulnerability Database
• CVSS changed · 6.5
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · → Modified
  Oct 13, 2026 · NIST National Vulnerability Database
• Record created in this database
  Oct 13, 2026 · NIST National Vulnerability Database
• 2021
• CVE published
  Aug 8, 2021 · mitre

Source activity

Repeated readings are counted rather than listed.

• 1× References added · Oct 13, 2026 – Oct 13, 2026
• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

9 on the record

• cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4
  Mailing List, Patch, Vendor Advisory, x_refsource_MISC, NIST National Vulnerability Database
• github.com/torvalds/linux/commit/dd99e9f98fbf423ff6d365b37a98e8879170f17c
  Patch, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
• github.com/advisories/GHSA-2crj-6275-fwfr
  GitHub Security Advisories
• nvd.nist.gov/vuln/detail/CVE-2021-38199
  GitHub Security Advisories
• security.netapp.com/advisory/ntap-20210902-0010/
  Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
• security.netapp.com/advisory/ntap-20210902-0010
  GitHub Security Advisories
• lists.debian.org/debian-lts-announce/2021/12/msg00012.html
  Mailing List, Third Party Advisory, mailing-list, x_refsource_MLIST, NIST National Vulnerability Database
• lists.debian.org/debian-lts-announce/2021/10/msg00010.html
  Mailing List, Third Party Advisory, mailing-list, x_refsource_MLIST, NIST National Vulnerability Database
• www.debian.org/security/2021/dsa-4978
  Third Party Advisory, vendor-advisory, x_refsource_DEBIAN, NIST National Vulnerability Database

Elsewhere on this site

Related CVEs (same products)

• Medium CVE-2026-98164 KVM: x86/mmu: Check write tracking in all address spaces 16d
• High CVE-2026-98163 cgroup: Avoid iteration of dying tasks with zero refcount 19d
• Medium CVE-2026-98162 smb/server: fix tree connection leak in smb2_tree_connect() 20d
• High CVE-2026-98156 drm/virtio: use the DMA API for resource backing on Xen 20d
• Medium CVE-2026-98159 wifi: mt76: mt7921: validate CLC firmware records 20d
• Medium CVE-2026-98137 ntfs: treat any nonzero dio zero-range return as an error 20d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No CWE classification.
• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2021-38199 is "fs/nfs/nfs4client.c in the Linux kernel before 5.13.4 has incorrect connection-setup ordering,...", rated Medium. It affects Debian Linux (Debian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. EPSS 1.25% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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