CVE-2017-16844: Heap-based buffer overflow in the loadbuf function in formisc.c in formail in procmail 3.22 allows remote atta

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2017-16844 is a critical-severity flaw (CVSS 9.8) affecting procmail. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Heap-based buffer overflow in the loadbuf function in formisc.c in formail in procmail 3.22 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted e-mail message because of a hardcoded realloc size, a different vulnerability than CVE-2014-3618.

Why this priority

Critical severity
EPSS top 4%: very likely to be exploited
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	12.2% (top 4%)
CISA exploited list	No
Weakness	CWE-119
Published	2017-11-16
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: procmail

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

Am I affected?

Timeline

2017-11-16 15:29 UTCPublished CVE record published
2026-06-17 01:10 UTCUpdated Record last modified

procmail procmail DOWNGRADE

Affected: 3.22

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.22

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.22 (Debian / Ubuntu)

apt-cache madison procmail sudo apt install procmail=<VERSION_BEFORE_3.22> sudo apt-mark hold procmail

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

dnf --showduplicates list procmail sudo dnf downgrade procmail-<VERSION_BEFORE_3.22> sudo dnf versionlock add procmail

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.

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-2017-16844?

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

Is CVE-2017-16844 being exploited?

CVE-2017-16844 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-2017-16844 affect?

CVE-2017-16844 affects procmail. Severity is critical (CVSS 9.8). Heap-based buffer overflow in the loadbuf function in formisc.c in formail in procmail 3.22 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted e-mail message because of

How urgent is CVE-2017-16844?

Priority 63/100. Critical severity; EPSS top 4%: very likely to be exploited; Remotely exploitable, no login, no user action

Related CVEs

CVE-2014-3618 HIGH 7.5 DOWNGRADE MITIGATE Heap-based buffer overflow in formisc.c in formail in procmail 3.22 allows remote attackers to cause a denial

References

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