How severe is CVE-2025-68699?

CVE-2025-68699 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2025-68699 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-68699?

CVE-2025-68699 affects Emqx Nanomq. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-68699?

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

Does CVE-2025-68699 have an EU (EUVD) identifier?

Yes. CVE-2025-68699 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-206782.

When was CVE-2025-68699 published?

CVE-2025-68699 was published on 2026-02-04 and last updated on 2026-06-17.

CVE-2025-68699

CVE-2025-68699 is a medium-severity vulnerability in Emqx Nanomq with a CVSS 3.x base score of 6.5. 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-476.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (18th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-206782
Weakness: CWE-476
Affected product: Emqx Nanomq
Published: 2026-02-04
Last modified: 2026-06-17

Description

NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. In version 0.24.6, NanoMQ has a protocol parsing / forwarding inconsistency when handling shared subscriptions ($share/). A malformed SUBSCRIBE topic such as $share/ab (missing the second /) is not strictly validated during the subscription stage, so the invalid Topic Filter is stored into the subscription table. Later, when any PUBLISH matches this subscription, the broker send path (nmq_pipe_send_start_v4/v5) performs a second $share/ parsing using strchr() and increments the returned pointer without NULL checks. If the second strchr() returns NULL, sub_topic++ turns the pointer into an invalid address (e.g. 0x1). This invalid pointer is then passed into topic_filtern(), which triggers strlen() and crashes with SIGSEGV. The crash is stable and remotely triggerable. This issue has been patched in version 0.24.7.

Frequently asked questions

What is CVE-2025-68699?: NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. In version 0.24.6, NanoMQ has a protocol parsing / forwarding inconsistency when handling shared subscriptions ($share/). A malformed SUBSCRIBE topic such as $share/ab (missing the second /) is not strictly validated during the subscription stage, so the invalid Topic Filter is stored into the subscription table. Later, when any PUBLISH matches this subscription, the broker send path (nmq_pipe_send_start_v4/v5) performs a second $share/ parsing using strchr() and increments the returned pointer without NULL checks. If the second strchr() returns NULL, sub_topic++ turns the pointer into an invalid address (e.g. 0x1). This invalid pointer is then passed into topic_filtern(), which triggers strlen() and crashes with SIGSEGV. The crash is stable and remotely triggerable. This issue has been patched in version 0.24.7.
How severe is CVE-2025-68699?: CVE-2025-68699 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-68699 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-68699?: CVE-2025-68699 affects Emqx Nanomq. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-68699?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-68699 have an EU (EUVD) identifier?: Yes. CVE-2025-68699 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-206782.
When was CVE-2025-68699 published?: CVE-2025-68699 was published on 2026-02-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:emqx:nanomq:0.24.6:*:*:*:*:*:*:*

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