CVE-2016-5823: The icalproperty_new_clone function in libical 0.47 and 1.0 allows remote attackers to cause a denial of servi

Routine

MEDIUM 5.5DOWNGRADE

CVE-2016-5823 is a medium-severity flaw (CVSS 5.5) affecting libical. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The icalproperty_new_clone function in libical 0.47 and 1.0 allows remote attackers to cause a denial of service (use-after-free) via a crafted ics file.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-416
Published	2017-01-27
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: libical project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-01-27 22:59 UTCPublished CVE record published
2026-06-17 00:50 UTCUpdated Record last modified

libical project libical DOWNGRADE

Affected: 0.47 · 1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.47

1. Check installed version

apt-cache policy libical || rpm -q libical || libical --version

2. No fixed release: DOWNGRADE to a release before 0.47 (Debian / Ubuntu)

apt-cache madison libical sudo apt install libical=<VERSION_BEFORE_0.47> sudo apt-mark hold libical

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libical sudo dnf downgrade libical-<VERSION_BEFORE_0.47> sudo dnf versionlock add libical

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2016-5823?

libical: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2016-5823 being exploited?

CVE-2016-5823 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2016-5823 affect?

CVE-2016-5823 affects libical. Severity is medium (CVSS 5.5). The icalproperty_new_clone function in libical 0.47 and 1.0 allows remote attackers to cause a denial of service (use-after-free) via a crafted ics file.

How urgent is CVE-2016-5823?

Priority 35/100. No elevated risk signals yet.

Related CVEs

CVE-2016-9584 CRITICAL 9.1 UPGRADE libical allows remote attackers to cause a denial of service (use-after-free) and possibly read heap memory vi
CVE-2016-5827 HIGH 7.5 DOWNGRADE The icaltime_from_string function in libical 0.47 and 1.0 allows remote attackers to cause a denial of service
CVE-2016-5826 HIGH 7.5 DOWNGRADE The parser_get_next_char function in libical 0.47 and 1.0 allows remote attackers to cause a denial of service
CVE-2016-5825 MEDIUM 5.5 DOWNGRADE The icalparser_parse_string function in libical 0.47 and 1.0 allows remote attackers to cause a denial of serv
CVE-2016-5824 MEDIUM 5.5 DOWNGRADE MITIGATE libical 1.0 allows remote attackers to cause a denial of service (use-after-free) via a crafted ics file.

References

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