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No exploitation reportedFix available

CVE-2021-38604

No exploitation reported by the sources we read.

  • Published2021-08-12
  • WeaknessCWE-476

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2021-08-1216:15CVE publishedNVD

Versions per branch

NVD
Oracle enterprise operations monitor
BranchAffectedFixed in
4.3= 4.3no fix published
4.4= 4.4no fix published
5.0= 5.0no fix published
Oracle communications cloud native core network repository function
BranchAffectedFixed in
22.1= 22.1.2no fix published
22.2= 22.2.0no fix published
Fedoraproject fedora
BranchAffectedFixed in
35.x= 35no fix published

5 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • glibcTuxCare:OracleLinux:6all versions · fixed in 2.12-2.213.el6.cloudlinux.elsand 6 other packages
  • glibcTuxCare:CentOS:6all versions · fixed in 2.12-2.213.el6.cloudlinux.elsand 6 other packages
  • glibcopenEuler:20.03-LTS-SP2all versions · fixed in 2.28-77.oe1
  • glibcopenEuler:20.03-LTS-SP1all versions · fixed in 2.28-77.oe1
  • glibcMageia:8all versions · fixed in 2.32-18.mga8
  • glibcAzure Linux:2all versions · fixed in 2.35-1
  • glibc-2.34MinimOSall versions · fixed in 0and 16 other packages
  • libc6TuxCare:Ubuntu:16.04all versions · fixed in 2.23-0ubuntu11.4and 14 other packages

Vendor advisories

  • CVE-2021-38604 Red Hat Product Security

    glibc: NULL pointer dereference in helper_thread() in mq_notify.c while handling NOTIFY_REMOVED messages

  • ICSA-23-348-10 CISA5 known affected

    Siemens SIMATIC S7-1500

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) · +2 more

  • SSA-398330 Siemens ProductCERT5 known affected

    SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= V3.1.0 < V3.1.5 · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= V3.1.0 < V3.1.5 · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= V3.1.0 < V3.1.5 · +2 more

  • ICSA-23-166-10 CISA1 known affected

    Siemens SIMATIC S7-1500 TM MFP BIOS

    SIMATIC S7-1500 TM MFP - BIOS

  • SSA-831302 Siemens ProductCERT1 known affected

    SSA-831302: Vulnerabilities in the BIOS of the SIMATIC S7-1500 TM MFP before V1.3.0

    SIMATIC S7-1500 TM MFP - BIOS

Full record on NVD

Fix

  1. Vendor fix CISA ICSA-23-348-10 · 5 productsUpdate to V3.1.5 or later version
  2. Vendor fix Siemens ProductCERT SSA-398330 · 1 productUpdate to V3.1.5 or later version
  3. Vendor fix Siemens ProductCERT SSA-831302 · 1 productUpdate to V1.3.0 or later version
  4. Vendor fix CISA ICSA-23-166-10 · 1 productUpdate to V1.3.0 or later version
  5. Workaround from the vendor Siemens ProductCERT SSA-831302 · 1 productOnly build and run applications from trusted sources
  6. Workaround from the vendor CISA ICSA-23-166-10 · 1 productOnly build and run applications from trusted sources

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2021-08-12
Last Modified
2026-10-14
NVD status
Modified
GitHub Advisory
GHSA-p3v7-wjmc-7fh8

Frequently asked questions

What is CVE-2021-38604?

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.

Is CVE-2021-38604 actively exploited?

Active exploitation of CVE-2021-38604 has not been confirmed. Its EPSS score was 3.7% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-38604?

CVE-2021-38604 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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