CVE-2019-19906: cyrus-sasl (aka Cyrus SASL) 2.1.27 has an out-of-bounds write leading to unauthenticated remote denial-of-serv

Q: How do I fix CVE-2019-19906?

cyrus-sasl: upgrade to 2.1.28; debian linux: mitigate or apply the listed mitigation; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2019-19906 being exploited?

CVE-2019-19906 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-2019-19906 affect?

CVE-2019-19906 affects cyrus-sasl, debian linux, ubuntu linux. Severity is high (CVSS 7.5). cyrus-sasl (aka Cyrus SASL) 2.1.27 has an out-of-bounds write leading to unauthenticated remote denial-of-service in OpenLDAP via a malformed LDAP packet. The OpenLDAP crash is ultimately caused by an off-by-one error in _sasl_add_string in

Q: How urgent is CVE-2019-19906?

Priority 65/100. High severity; EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2019-19906 is a high-severity flaw (CVSS 7.5) affecting cyrus-sasl, debian linux, ubuntu linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

cyrus-sasl (aka Cyrus SASL) 2.1.27 has an out-of-bounds write leading to unauthenticated remote denial-of-service in OpenLDAP via a malformed LDAP packet. The OpenLDAP crash is ultimately caused by an off-by-one error in _sasl_add_string in common.c in cyrus-sasl.

Why this priority

High severity
EPSS top 5%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	8.0% (top 5%)
CISA exploited list	No
Weakness	CWE-193, CWE-787
Published	2019-12-19
Last modified	2026-10-14

Publisher (CNA): MITRE · Vendor: apple · canonical · cyrusimap · debian · fedoraproject · redhat

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-12-19 18:15 UTCPublished CVE record published
2026-10-14 08:16 UTCUpdated Record last modified

cyrusimap cyrus-sasl UPGRADE

Affected: < 2.1.28

Fixed in: 2.1.28

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy cyrus-sasl || rpm -q cyrus-sasl || cyrus-sasl --version

2. UPGRADE to 2.1.28 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade cyrus-sasl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cyrus-sasl

Note

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

debian debian linux MITIGATE

Affected: 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

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.

canonical ubuntu linux MITIGATE

Affected: 12.04 · 14.04 · 16.04 · 18.04 · 19.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.04

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.

fedoraproject fedora MITIGATE

Affected: 31 · 32

Fixed in: no fixed release known

Safe to downgrade to: a release before 31

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.

redhat jboss enterprise web server DOWNGRADE

Affected: 2.0.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0.0

1. Check installed version

apt-cache policy jboss-enterprise-web-server || rpm -q jboss-enterprise-web-server || jboss-enterprise-web-server --version

2. No fixed release: DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison jboss-enterprise-web-server sudo apt install jboss-enterprise-web-server=<VERSION_BEFORE_2.0.0> sudo apt-mark hold jboss-enterprise-web-server

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

dnf --showduplicates list jboss-enterprise-web-server sudo dnf downgrade jboss-enterprise-web-server-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add jboss-enterprise-web-server

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.

apple mac os x UPGRADE

Affected: 10.14.6 · < 10.13.6 · >= 10.13.0 and < 10.13.6 · >= 10.15.0 and < 10.15.6 · 10.13.6 · 10.13.6 security_update_2018-002 · 10.13.6 security_update_2018-003 · 10.13.6 security_update_2019-001

Fixed in: 10.13.6, 10.15.6

Safe to downgrade to: a release before 10.13.0

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-2019-19906?

cyrus-sasl: upgrade to 2.1.28; debian linux: mitigate or apply the listed mitigation; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-19906 being exploited?

CVE-2019-19906 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-2019-19906 affect?

CVE-2019-19906 affects cyrus-sasl, debian linux, ubuntu linux. Severity is high (CVSS 7.5). cyrus-sasl (aka Cyrus SASL) 2.1.27 has an out-of-bounds write leading to unauthenticated remote denial-of-service in OpenLDAP via a malformed LDAP packet. The OpenLDAP crash is ultimately caused by an off-by-one error in _sasl_add_string in

How urgent is CVE-2019-19906?

Priority 65/100. High severity; EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities · OpenLDAP vulnerabilities · JBoss and WildFly vulnerabilities

Related CVEs

CVE-2022-24407 HIGH 8.8 UPGRADE MITIGATE In Cyrus SASL 2.1.17 through 2.1.27 before 2.1.28, plugins/sql.c does not escape the password for a SQL INSERT
CVE-2020-8032 MEDIUM 6.7 UPGRADE A Insecure Temporary File vulnerability in the packaging of cyrus-sasl of openSUSE Factory allows local attack
CVE-2013-4122 MEDIUM 4.3 UPGRADE Cyrus SASL 2.1.23, 2.1.26, and earlier does not properly handle when a NULL value is returned upon an error by
CVE-2009-0688 HIGH 7.5 UPGRADE Multiple buffer overflows in the CMU Cyrus SASL library before 2.1.23 might allow remote attackers to execute

References

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