CVE-2020-16118: In GNOME Balsa before 2.6.0, a malicious server operator or man in the middle can trigger a NULL pointer deref

This week

HIGH 7.5REMOTEUPGRADEDOWNGRADEMITIGATE

CVE-2020-16118 is a high-severity flaw (CVSS 7.5) affecting balsa, backports sle, leap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In GNOME Balsa before 2.6.0, a malicious server operator or man in the middle can trigger a NULL pointer dereference and client crash by sending a PREAUTH response to imap_mbox_connect in libbalsa/imap/imap-handle.c.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

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	2.1% (top 19%)
CISA exploited list	No
Weakness	CWE-476
Published	2020-07-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: gnome · opensuse

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

Am I affected?

Timeline

2020-07-29 18:15 UTCPublished CVE record published
2026-06-17 02:57 UTCUpdated Record last modified

gnome balsa UPGRADE

Affected: < 2.6.0

Fixed in: 2.6.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.6.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade balsa

Note

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

opensuse backports sle DOWNGRADE

Affected: 15.0 sp1

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.0

1. Check installed version

apt-cache policy backports-sle || rpm -q backports-sle || backports-sle --version

2. No fixed release: DOWNGRADE to a release before 15.0 (Debian / Ubuntu)

apt-cache madison backports-sle sudo apt install backports-sle=<VERSION_BEFORE_15.0> sudo apt-mark hold backports-sle

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

dnf --showduplicates list backports-sle sudo dnf downgrade backports-sle-<VERSION_BEFORE_15.0> sudo dnf versionlock add backports-sle

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.

opensuse leap MITIGATE

Affected: 15.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.1

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-2020-16118?

balsa: upgrade to 2.6.0; backports sle: downgrade or apply the listed mitigation; leap: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-16118 being exploited?

CVE-2020-16118 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-2020-16118 affect?

CVE-2020-16118 affects balsa, backports sle, leap. Severity is high (CVSS 7.5). In GNOME Balsa before 2.6.0, a malicious server operator or man in the middle can trigger a NULL pointer dereference and client crash by sending a PREAUTH response to imap_mbox_connect in libbalsa/imap/imap-handle.c.

How urgent is CVE-2020-16118?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2020-13645 MEDIUM 6.5 UPGRADE UPGRADE In GNOME glib-networking through 2.64.2, the implementation of GTlsClientConnection skips hostname verificatio
CVE-2007-5007 MEDIUM 6.8 DOWNGRADE Stack-based buffer overflow in the ir_fetch_seq function in balsa before 2.3.20 might allow remote IMAP server
CVE-2003-0300 MEDIUM 5.0 DOWNGRADE DOWNGRADE The IMAP Client for Sylpheed 0.8.11 allows remote malicious IMAP servers to cause a denial of service (crash)
CVE-2003-0299 HIGH 7.5 DOWNGRADE DOWNGRADE The IMAP Client, as used in mutt 1.4.1 and Balsa 2.0.10, allows remote malicious IMAP servers to cause a denia

References

← Back to latest CVEs