CVE-2019-15523: An issue was discovered in LINBIT csync2 through 2.0

Q: How do I fix CVE-2019-15523?

csync2: upgrade to newer than 2.0; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2019-15523 being exploited?

CVE-2019-15523 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2019-15523 affect?

CVE-2019-15523 affects csync2, debian linux. Severity is medium (CVSS 5.3). An issue was discovered in LINBIT csync2 through 2.0. It does not correctly check for the return value GNUTLS_E_WARNING_ALERT_RECEIVED of the gnutls_handshake() function. It neglects to call this function again, as required by the design of

Q: How urgent is CVE-2019-15523?

Priority 46/100. Remotely exploitable, no login, no user action; On your watchlist

This month

MEDIUM 5.3REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2019-15523 is a medium-severity flaw (CVSS 5.3) affecting csync2, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in LINBIT csync2 through 2.0. It does not correctly check for the return value GNUTLS_E_WARNING_ALERT_RECEIVED of the gnutls_handshake() function. It neglects to call this function again, as required by the design of the API.

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.3% (top 29%)
CISA exploited list	No
Weakness	CWE-252
Published	2020-12-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · linbit

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

Am I affected?

Timeline

2020-12-30 21:15 UTCPublished CVE record published
2026-06-17 02:20 UTCUpdated Record last modified

linbit csync2 UPGRADE

Affected: <= 2.0

Fixed in: newer than 2.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy csync2 || rpm -q csync2 || csync2 --version

2. UPGRADE to newer than 2.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade csync2

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade csync2

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2019-15523?

csync2: upgrade to newer than 2.0; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-15523 being exploited?

CVE-2019-15523 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-2019-15523 affect?

CVE-2019-15523 affects csync2, debian linux. Severity is medium (CVSS 5.3). An issue was discovered in LINBIT csync2 through 2.0. It does not correctly check for the return value GNUTLS_E_WARNING_ALERT_RECEIVED of the gnutls_handshake() function. It neglects to call this function again, as required by the design of

How urgent is CVE-2019-15523?

Priority 46/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · GnuTLS vulnerabilities

Related CVEs

CVE-2019-15522 CRITICAL 9.8 UPGRADE An issue was discovered in LINBIT csync2 through 2.0

References

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