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Fencer Vulns
high 7.5

CVE-2021-41688 json

DCMTK through 3.6.6 does not handle memory free properly.

published 2022-06-28 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-28700

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 79%
public exploits
0
none known

Summary

DCMTK through 3.6.6 does not handle memory free properly. The object in the program is free but its address is still used in other locations. Sending specific requests to the dcmqrdb program will incur a double free. An attacker can use it to launch a DoS attack.

Patch / fix

  • dcmtk Debian 14, Debian 13, Debian 12 3.6.7-1

debian advisories DEBIAN-CVE-2021-41688

  • dcmtk Ubuntu 20.04 LTS 3.6.4-2.1ubuntu0.1
  • dcmtk Ubuntu Pro 16.04 LTS 3.6.1~20150924-5ubuntu0.1~esm1
  • dcmtk Ubuntu Pro 18.04 LTS 3.6.2-3ubuntu0.1~esm1
  • dcmtk Ubuntu Pro 20.04 LTS 3.6.4-2.1ubuntu0.1~esm1
  • dcmtk Ubuntu Pro 22.04 LTS 3.6.6-5ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-41688

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-41688 updated cvss 7.5

dcmtk: a double free allows for a DoS

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

1.84% chance of exploitation in the next 30 days, higher than 79% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.