CVE-2018-16789: libhttp/url.c in shellinabox through 2.20 has an implementation flaw in the HTTP request parsing logic

Q: How do I fix CVE-2018-16789?

shellinabox: upgrade to newer than 2.20. Exact commands for each OS are on this page.

Q: Is CVE-2018-16789 being exploited?

CVE-2018-16789 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-2018-16789 affect?

CVE-2018-16789 affects shellinabox. Severity is high (CVSS 7.5). libhttp/url.c in shellinabox through 2.20 has an implementation flaw in the HTTP request parsing logic. By sending a crafted multipart/form-data HTTP request, an attacker could exploit this to force shellinaboxd into an infinite loop, exhau

Q: How urgent is CVE-2018-16789?

Priority 60/100. High severity; EPSS top 7%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2018-16789 is a high-severity flaw (CVSS 7.5) affecting shellinabox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

libhttp/url.c in shellinabox through 2.20 has an implementation flaw in the HTTP request parsing logic. By sending a crafted multipart/form-data HTTP request, an attacker could exploit this to force shellinaboxd into an infinite loop, exhausting available CPU resources and taking the service down.

Why this priority

High severity
EPSS top 7%: very likely to be exploited
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	6.0% (top 7%)
CISA exploited list	No
Weakness	CWE-835
Published	2019-03-21
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: shellinabox project

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

Am I affected?

Timeline

2019-03-21 16:00 UTCPublished CVE record published
2026-06-17 01:44 UTCUpdated Record last modified

shellinabox project shellinabox UPGRADE

Affected: <= 2.20

Fixed in: newer than 2.20

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 2.20 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade shellinabox

Note

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

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-2018-16789?

shellinabox: upgrade to newer than 2.20. Exact commands for each OS are on this page.

Is CVE-2018-16789 being exploited?

CVE-2018-16789 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-2018-16789 affect?

CVE-2018-16789 affects shellinabox. Severity is high (CVSS 7.5). libhttp/url.c in shellinabox through 2.20 has an implementation flaw in the HTTP request parsing logic. By sending a crafted multipart/form-data HTTP request, an attacker could exploit this to force shellinaboxd into an infinite loop, exhau

How urgent is CVE-2018-16789?

Priority 60/100. High severity; EPSS top 7%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

References

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