How severe is CVE-2023-0809?

CVE-2023-0809 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2023-0809 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-0809?

CVE-2023-0809 affects Eclipse Mosquitto. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-0809?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-0809 published?

CVE-2023-0809 was published on 2023-10-02 and last updated on 2026-06-17.

CVE-2023-0809

CVE-2023-0809 is a medium-severity vulnerability in Eclipse Mosquitto with a CVSS 3.x base score of 5.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: Medium (CVSS 3.x base score 5.8)
EPSS exploit prediction: 1% (52nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Eclipse Mosquitto
Published: 2023-10-02
Last modified: 2026-06-17

Description

In Mosquitto before 2.0.16, excessive memory is allocated based on malicious initial packets that are not CONNECT packets.

Frequently asked questions

What is CVE-2023-0809?: In Mosquitto before 2.0.16, excessive memory is allocated based on malicious initial packets that are not CONNECT packets.
How severe is CVE-2023-0809?: CVE-2023-0809 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2023-0809 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-0809?: CVE-2023-0809 affects Eclipse Mosquitto. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-0809?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-0809 published?: CVE-2023-0809 was published on 2023-10-02 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:eclipse:mosquitto:*:*:*:*:*:*:*:*

More vulnerabilities in Eclipse Mosquitto

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CVE-2023-5632 — High (CVSS 7.5): In Eclipse Mosquito before and including 2.0.5, establishing a connection to the mosquitto server without sending data…
CVE-2023-28366 — High (CVSS 7.5): The broker in Eclipse Mosquitto 1.3.2 through 2.x before 2.0.16 has a memory leak that can be abused remotely when a…

All CVEs affecting Eclipse Mosquitto →

Other CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities

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CVE-2026-82439 — Critical (CVSS 9.8): Description The DRPC server kept a map from function name to request queue and created an entry the first time…
CVE-2026-47891 — Critical (CVSS 9.8): A Spring WebFlux application that relies on the Aalto XML processor to parse XML input does not correctly enforce the…
CVE-2026-74878 — Critical (CVSS 9.8): openssl_encrypt versions before 1.4.0 use an in-memory rate limiter for TOTP brute-force protection that is not shared…
CVE-2026-31283 — Critical (CVSS 9.8): In Totara LMS v19.1.5 and before, the forgot password API does not implement rate limiting for the target email…
CVE-2020-37067 — Critical (CVSS 9.8): Filetto 1.0 FTP server contains a denial of service vulnerability in the FEAT command processing that allows attackers…

Browse all CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

175.195.238.137 (ipv4-addr)
98.122.215.23 (ipv4-addr)
182.95.217.202 (ipv4-addr)
182.95.106.102 (ipv4-addr)
128.185.208.42 (ipv4-addr)
122.186.202.58 (ipv4-addr)
182.95.190.150 (ipv4-addr)
222.118.59.16 (ipv4-addr)