How severe is CVE-2019-9749?

CVE-2019-9749 has a CVSS 3.x base score of 7.5, rated high 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 high.

Is CVE-2019-9749 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-9749?

CVE-2019-9749 affects Treasuredata Fluent Bit. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2019-9749?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2019-9749 published?

CVE-2019-9749 was published on 2019-03-13 and last updated on 2026-06-17.

CVE-2019-9749

CVE-2019-9749 is a high-severity vulnerability in Treasuredata Fluent Bit with a CVSS 3.x base score of 7.5. 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-681.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-681
Affected product: Treasuredata Fluent Bit
Published: 2019-03-13
Last modified: 2026-06-17

Description

An issue was discovered in the MQTT input plugin in Fluent Bit through 1.0.4. When this plugin acts as an MQTT broker (server), it mishandles incoming network messages. After processing a crafted packet, the plugin's mqtt_packet_drop function (in /plugins/in_mqtt/mqtt_prot.c) executes the memmove() function with a negative size parameter. That leads to a crash of the whole Fluent Bit server via a SIGSEGV signal.

Frequently asked questions

What is CVE-2019-9749?: An issue was discovered in the MQTT input plugin in Fluent Bit through 1.0.4. When this plugin acts as an MQTT broker (server), it mishandles incoming network messages. After processing a crafted packet, the plugin's mqtt_packet_drop function (in /plugins/in_mqtt/mqtt_prot.c) executes the memmove() function with a negative size parameter. That leads to a crash of the whole Fluent Bit server via a SIGSEGV signal.
How severe is CVE-2019-9749?: CVE-2019-9749 has a CVSS 3.x base score of 7.5, rated high 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 high.
Is CVE-2019-9749 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-9749?: CVE-2019-9749 affects Treasuredata Fluent Bit. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-9749?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-9749 published?: CVE-2019-9749 was published on 2019-03-13 and last updated on 2026-06-17.

References

https://github.com/fluent/fluent-bit/issues/1135

Affected products (1)

cpe:2.3:a:treasuredata:fluent_bit:*:*:*:*:*:*:*:*

More vulnerabilities in Treasuredata Fluent Bit

CVE-2024-4323 — Critical (CVSS 9.8): A memory corruption vulnerability in Fluent Bit versions 2.0.7 thru 3.0.3. This issue lies in the embedded http…
CVE-2021-36088 — Critical (CVSS 9.8): Fluent Bit (aka fluent-bit) 1.7.0 through 1.7.4 has a double free in flb_free (called from flb_parser_json_do and…
CVE-2025-12977 — Critical (CVSS 9.1): Fluent Bit in_http, in_splunk, and in_elasticsearch input plugins fail to sanitize tag_key inputs. An attacker with…
CVE-2025-12970 — High (CVSS 8.8): The extract_name function in Fluent Bit in_docker input plugin copies container names into a fixed size stack buffer…
CVE-2021-46879 — High (CVSS 7.8): An issue was discovered in Treasure Data Fluent Bit 1.7.1, a wrong variable is used to get the msgpack data resulting…
CVE-2021-46878 — High (CVSS 7.8): An issue was discovered in Treasure Data Fluent Bit 1.7.1, erroneous parsing in flb_pack_msgpack_to_json_format leads…

All CVEs affecting Treasuredata Fluent Bit →

Other CWE-681 vulnerabilities

CVE-2022-40138 — Critical (CVSS 9.8): An integer conversion error in Hermes bytecode generation, prior to commit 6aa825e480d48127b480b08d13adf70033237097,…
CVE-2021-36357 — Critical (CVSS 9.8): An issue was discovered in OpenPOWER 2.6 firmware. unpack_timestamp() calls le32_to_cpu() for endian conversion of a…
CVE-2021-38187 — Critical (CVSS 9.8): An issue was discovered in the anymap crate through 0.12.1 for Rust. It violates soundness via conversion of a *u8 to a…
CVE-2019-19317 — Critical (CVSS 9.8): lookupName in resolve.c in SQLite 3.30.1 omits bits from the colUsed bitmask in the case of a generated column, which…
CVE-2019-14842 — Critical (CVSS 9.8): Structured reply is a feature of the newstyle NBD protocol allowing the server to send a reply in chunks. A bounds…
CVE-2018-8786 — Critical (CVSS 9.8): FreeRDP prior to version 2.0.0-rc4 contains an Integer Truncation that leads to a Heap-Based Buffer Overflow in…

Browse all CWE-681 vulnerabilities →