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FedoraOperating system · Fedoraproject

CVE-2021-38604

HIGH · 7.5 CVSS v3.1 Published 2021-08-12
Fix available
A fix is available. Upgrade to after 2.34 or later.
See remediation →
84/100
Remediation priority · High
Public exploit Remotely reachable No privileges Zero-click Patch available

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
In librt in the GNU C Library (aka glibc) through 2.34, sysdeps/unix/sysv/linux/mq_notify.c mishandles certain NOTIFY_REMOVED data, leading to a NULL pointer dereference. NOTE: this vulnerability was introduced as a side effect of the CVE-2021-33574 fix.

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
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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
FedoraOperating system
Affected:= 35
GlibcFramework / library
Affected:<= 2.34
Communications Cloud Native Core Binding Support FunctionApplication
Affected:= 22.1.3
Communications Cloud Native Core Network Function Cloud Native EnvironmentApplication
Affected:= 22.1.0
Communications Cloud Native Core Network Repository FunctionApplication
Affected:= 22.1.2= 22.2.0
Communications Cloud Native Core Security Edge Protection ProxyWeb browser
Affected:= 22.1.1
Communications Cloud Native Core Unified Data RepositoryApplication
Affected:= 22.2.0
Enterprise Operations MonitorApplication
Affected:= 4.3= 4.4= 5.0

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 a release after 2.34
Vendor patch sourceware.org →
Recommended fix High confidence

glibc version greater than 2.34 (e.g., glibc 2.35 or later)

  1. 1. Identify the current glibc version installed on the system using: rpm -q glibc or ldd --version
  2. 2. For Fedora systems: Run 'dnf update glibc' to upgrade to a fixed version
  3. 3. For other Linux distributions: Update the system package manager to install glibc > 2.34
  4. 4. After upgrading, verify the new version with: ldd --version
  5. 5. Reboot the system to ensure the new glibc libraries are loaded
  6. 6. Test critical applications to confirm compatibility with the updated glibc
Caveat Major glibc upgrades can cause compatibility issues with older binaries or libraries compiled against the previous glibc version; test thoroughly before production deployment

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

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $3,200. 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-2021-38604 in production — separate from our analysis above.

No notes yet

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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