CVE-2019-17502: Hydra through 0.1.8 has a NULL pointer dereference and daemon crash when processing POST requests that lack a

Q: How do I fix CVE-2019-17502?

hydra: upgrade to newer than 0.1.8. Exact commands for each OS are on this page.

Q: Is CVE-2019-17502 being exploited?

CVE-2019-17502 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-2019-17502 affect?

CVE-2019-17502 affects hydra. Severity is high (CVSS 7.5). Hydra through 0.1.8 has a NULL pointer dereference and daemon crash when processing POST requests that lack a Content-Length header. read.c, request.c, and util.c contribute to this. The process_header_end() function calls boa_atoi(), which

Q: How urgent is CVE-2019-17502?

Priority 56/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2019-17502 is a high-severity flaw (CVSS 7.5) affecting hydra. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Hydra through 0.1.8 has a NULL pointer dereference and daemon crash when processing POST requests that lack a Content-Length header. read.c, request.c, and util.c contribute to this. The process_header_end() function calls boa_atoi(), which ultimately calls atoi() on a NULL pointer.

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	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-476
Published	2019-10-12
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: hydra project

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

Am I affected?

Timeline

2019-10-12 20:15 UTCPublished CVE record published
2026-06-17 02:24 UTCUpdated Record last modified

hydra project hydra UPGRADE

Affected: <= 0.1.8

Fixed in: newer than 0.1.8

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 0.1.8 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade hydra

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-2019-17502?

hydra: upgrade to newer than 0.1.8. Exact commands for each OS are on this page.

Is CVE-2019-17502 being exploited?

CVE-2019-17502 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-2019-17502 affect?

CVE-2019-17502 affects hydra. Severity is high (CVSS 7.5). Hydra through 0.1.8 has a NULL pointer dereference and daemon crash when processing POST requests that lack a Content-Length header. read.c, request.c, and util.c contribute to this. The process_header_end() function calls boa_atoi(), which

How urgent is CVE-2019-17502?

Priority 56/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

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References

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