CVE-2019-15699: An issue was discovered in app-layer-ssl.c in Suricata 4.1.4

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CRITICAL 9.1REMOTEDOWNGRADE

CVE-2019-15699 is a critical-severity flaw (CVSS 9.1) affecting suricata. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in app-layer-ssl.c in Suricata 4.1.4. Upon receiving a corrupted SSLv3 (TLS 1.2) packet, the parser function TLSDecodeHSHelloExtensions tries to access a memory region that is not allocated, because the expected length of HSHelloExtensions does not match the real length of the HSHelloExtensions part of the packet.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.6% (top 24%)
CISA exploited list	No
Weakness	CWE-125
Published	2019-09-24
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: suricata-ids

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

Am I affected?

Timeline

2019-09-24 20:15 UTCPublished CVE record published
2026-06-17 02:20 UTCUpdated Record last modified

suricata-ids suricata DOWNGRADE

Affected: 4.1.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.1.4

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.1.4 (Debian / Ubuntu)

apt-cache madison suricata sudo apt install suricata=<VERSION_BEFORE_4.1.4> sudo apt-mark hold suricata

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

dnf --showduplicates list suricata sudo dnf downgrade suricata-<VERSION_BEFORE_4.1.4> sudo dnf versionlock add suricata

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-2019-15699?

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

Is CVE-2019-15699 being exploited?

CVE-2019-15699 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-2019-15699 affect?

CVE-2019-15699 affects suricata. Severity is critical (CVSS 9.1). An issue was discovered in app-layer-ssl.c in Suricata 4.1.4. Upon receiving a corrupted SSLv3 (TLS 1.2) packet, the parser function TLSDecodeHSHelloExtensions tries to access a memory region that is not allocated, because the expected leng

How urgent is CVE-2019-15699?

Priority 56/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

Suricata and Snort vulnerabilities

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References

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