dbcve.org
Debian LinuxOperating system · Debian

CVE-2021-3999

HIGH · 7.8 CVSS v3.1 Published 2022-08-24
Fix available
A fix is available. Upgrade to 2.31 or later.
See remediation →
80/100
Remediation priority · High
Public exploit Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A flaw was found in glibc. An off-by-one buffer overflow and underflow in getcwd() may lead to memory corruption when the size of the buffer is exactly 1. A local attacker who can control the input buffer and size passed to getcwd() in a setuid program could use this flaw to potentially execute arbitrary code and escalate their privileges on the system.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Debian LinuxOperating system
Affected:= 10.0= 11.0
GlibcFramework / library
Affected:< 2.31
E Series Performance AnalyzerApplication
Affected:all versions
Nfs Plug InApplication
Affected:all versions
Ontap Select Deploy Administration UtilityApplication
Affected:all versions
H300s FirmwareOperating system
Affected:all versions
H500s FirmwareOperating system
Affected:all versions
H700s FirmwareOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.31 or later
Fixed in 2.31
Recommended fix High confidence

Glibc 2.31-13+deb10u2 (Debian 10) or 2.31-13+deb11u2 (Debian 11), or the fixed releases specified in NetApp security advisories for their respective products

  1. Update the system package list: sudo apt-get update
  2. Upgrade glibc to the fixed version: sudo apt-get install --upgrade libc6 (or sudo apt-get upgrade)
  3. Verify the installed glibc version matches or exceeds the fixed release (2.31-13+deb10u2 for Debian 10, 2.31-13+deb11u2 for Debian 11)
  4. For NetApp products (E Series Performance Analyzer, Nfs Plug In, Ontap Select Deploy Administration Utility), apply the corresponding NetApp security advisory patches from security.netapp.com
  5. For H300s/H500s/H700s firmware, apply firmware updates from NetApp's support portal
Caveat Upgrade of glibc is a system library update; ensure compatibility with application binaries. On setuid/setgid programs, verify normal operation after reboot.

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-3999 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data