CVE-2019-15717: Irssi 1.2.x before 1.2.2 has a use-after-free if the IRC server sends a double CAP.

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2019-15717 is a critical-severity flaw (CVSS 9.8) affecting irssi, ubuntu linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Irssi 1.2.x before 1.2.2 has a use-after-free if the IRC server sends a double CAP.

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-416
Published	2019-08-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: canonical · irssi

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

Am I affected?

Timeline

2019-08-29 17:15 UTCPublished CVE record published
2026-06-17 02:20 UTCUpdated Record last modified

irssi irssi UPGRADE

Affected: >= 1.2.0 and < 1.2.2

Fixed in: 1.2.2

Safe to downgrade to: a release before 1.2.0

1. Check installed version

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

2. UPGRADE to 1.2.2 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade irssi

Note

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

3. If no update is available yet, DOWNGRADE to a release before 1.2.0 (Debian / Ubuntu)

apt-cache madison irssi sudo apt install irssi=<VERSION_BEFORE_1.2.0> sudo apt-mark hold irssi

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list irssi sudo dnf downgrade irssi-<VERSION_BEFORE_1.2.0> sudo dnf versionlock add irssi

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.

canonical ubuntu linux MITIGATE

Affected: 19.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 19.04

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.

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-2019-15717?

irssi: upgrade to 1.2.2; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-15717 being exploited?

CVE-2019-15717 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-2019-15717 affect?

CVE-2019-15717 affects irssi, ubuntu linux. Severity is critical (CVSS 9.8). Irssi 1.2.x before 1.2.2 has a use-after-free if the IRC server sends a double CAP.

How urgent is CVE-2019-15717?

Priority 65/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Ubuntu vulnerabilities

Related CVEs

CVE-2023-29132 MEDIUM 5.3 UPGRADE Irssi 1.3.x and 1.4.x before 1.4.4 has a use-after-free because of use of a stale special collector reference
CVE-2019-5882 CRITICAL 9.8 UPGRADE MITIGATE Irssi 1.1.x before 1.1.2 has a use after free when hidden lines are expired from the scroll buffer.
CVE-2019-13045 HIGH 8.1 UPGRADE Irssi before 1.0.8, 1.1.x before 1.1.3, and 1.2.x before 1.2.1, when SASL is enabled, has a use after free whe
CVE-2018-7054 CRITICAL 9.8 UPGRADE MITIGATE An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1
CVE-2018-7053 CRITICAL 9.8 UPGRADE MITIGATE An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1

References

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