How severe is CVE-2025-10543?

No CVSS score has been assigned to CVE-2025-10543 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-10543?

CVE-2025-10543 affects the following packages: github.com/eclipse/paho.mqtt.golang (Go). Ecosystems affected: Go.

How do I fix CVE-2025-10543?

Update github.com/eclipse/paho.mqtt.golang to 1.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-10543 is resolved across your whole dependency graph.

How do I detect CVE-2025-10543 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/eclipse/paho.mqtt.golang, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-10543 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2025-10543?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-10543 can be triaged on real exposure rather than presence alone.

Is CVE-2025-10543 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-10543 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-10543?

CVE-2025-10543 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 14th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-10543?

CVE-2025-10543 is classified as CWE-197 (CWE-197), CWE-681 (CWE-681). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-10543 published, and has it been updated?

CVE-2025-10543 was published on December 2, 2025 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2025-10543 — paho.mqtt.golang

Fix: eclipse-paho/paho.mqtt.golang#714

CVE-2025-10543 is a CWE-197 vulnerability in github.com/eclipse/paho.mqtt.golang. A fix is available for github.com/eclipse/paho.mqtt.golang — see the affected versions and patch details below.

Eclipse Paho Go MQTT may incorrectly encode strings if length exceeds 65535 bytes

Also known asGHSA-32fw-gq77-f2f2GO-2025-4173

Published

Dec 2, 2025

Updated

Aug 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-10543.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs14th percentile — riskier than 14% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected

🐹github.com/eclipse/paho.mqtt.golang

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

The issue arises because the length of the data passed in was converted from an int64/int32 (depending upon CPU) to an int16 without checks for overflows. The int16 length was then written, followed by the data (e.g. topic). This meant that when the data (e.g. topic) was over 65535 bytes then the amount of data written exceeds what the length field indicates. This could lead to a corrupt packet, or mean that the excess data leaks into another field (e.g. topic leaks into message body).

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/eclipse/paho.mqtt.golang`	all versions	1.5.1`go get github.com/eclipse/paho.mqtt.golang@v1.5.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/eclipse/paho.mqtt.golang, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/eclipse/paho.mqtt.golang to 1.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-10543 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-10543 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2025-10543. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

In Eclipse Paho Go MQTT v3.1 library (paho.mqtt.golang) versions <=1.5.0 UTF-8 encoded strings, passed into the library, may be incorrectly encoded if their length exceeds 65535 bytes. This may lead to unexpected content in packets sent to the server (for example, part of an MQTT topic may leak into the message body in a PUBLISH packet). The issue arises because the length of the data passed in was converted from an int64/int32 (depending upon CPU) to an int16 without checks for overflows. The int16 length was then written, followed by the data (e.g. topic). This meant that when the data (e.

O3 Security · Impact-Aware SCA

Is CVE-2025-10543 in your dependencies?

O3 Security finds CVE-2025-10543 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works