CVE-2019-25364: MailCarrier 2.51 contains a buffer overflow vulnerability in the POP3 USER command that allows remote attacker

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2019-25364 is a critical-severity flaw (CVSS 9.8) affecting mailcarrier. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MailCarrier 2.51 contains a buffer overflow vulnerability in the POP3 USER command that allows remote attackers to execute arbitrary code. Attackers can send a crafted oversized buffer to the POP3 service, overwriting memory and potentially gaining remote system access.

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

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	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-121
Published	2026-02-18
Last modified	2026-06-17

Publisher (CNA): VulnCheck · Vendor: tabslab

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

Am I affected?

Timeline

2026-02-18 22:16 UTCPublished CVE record published
2026-06-17 02:32 UTCUpdated Record last modified

tabslab mailcarrier DOWNGRADE

Affected: 2.51

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.51

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.51 (Debian / Ubuntu)

apt-cache madison mailcarrier sudo apt install mailcarrier=<VERSION_BEFORE_2.51> sudo apt-mark hold mailcarrier

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

dnf --showduplicates list mailcarrier sudo dnf downgrade mailcarrier-<VERSION_BEFORE_2.51> sudo dnf versionlock add mailcarrier

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora ELN · intel-ipsec-mb · FIXED · 3.0.1-1.eln159 · FEDORA-2026-ca01077210 · source

sudo dnf upgrade --advisory=FEDORA-2026-ca01077210

Fedora 46 · complytime-providers · FIXED · 0.3.0-2.fc46 · FEDORA-2026-7c372be466 · source

sudo dnf upgrade --advisory=FEDORA-2026-7c372be466

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: www.exploit-db.com/exploits/47554

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-2019-25364?

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

Is CVE-2019-25364 being exploited?

CVE-2019-25364 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-2019-25364 affect?

CVE-2019-25364 affects mailcarrier. Severity is critical (CVSS 9.8). MailCarrier 2.51 contains a buffer overflow vulnerability in the POP3 USER command that allows remote attackers to execute arbitrary code. Attackers can send a crafted oversized buffer to the POP3 service, overwriting memory and potentially

How urgent is CVE-2019-25364?

Priority 63/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

CVE-2019-25646 CRITICAL 9.8 DOWNGRADE Tabs Mail Carrier 2.5.1 contains a buffer overflow vulnerability in the MAIL FROM SMTP command that allows rem

References

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