What is CVE-2019-19307?

CVE-2019-19307 is a critical-severity vulnerability in Cesanta Mongoose, classified under Out-of-bounds Read. CVSS score: 9.8/10. Published 2019-11-26.

How severe is CVE-2019-19307?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2019-19307 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Out-of-bounds Read in Cesanta Mongoose

CVE-2019-19307

An integer overflow in parse_mqtt in mongoose.c in Cesanta Mongoose 6.16 allows an attacker to achieve remote DoS (infinite loop), or possibly cause an out-of-bounds write, by sending a crafted MQTT protocol packet.

Vulnerability class: Buffer Overflow

Published 2019-11-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.416 (98.6th percentile), scored 2026-09-28.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.416 · newest: 0.416 · change: 0.000

Affected products

Cesanta Mongoose — versions 6.16

Weakness classification (CWE)

Public proof-of-concept exploits

asdyxcyxc/Hermes

References

github.com/cesanta/mongoose/issues/1055 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2019-19307?: CVE-2019-19307 is a critical-severity vulnerability in Cesanta Mongoose, classified under Out-of-bounds Read. CVSS score: 9.8/10. Published 2019-11-26.
How severe is CVE-2019-19307?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2019-19307 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.