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Fencer Vulns
medium 5.3

CVE-2025-10543 json

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

published 2025-12-02 11 mo ago modified 2026-10-18 21 d ago also GHSA-32fw-gq77-f2f2 , GO-2025-4173 , EUVD-2025-200211

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

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.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).

Patch / fix

  • go github.com/eclipse/paho.mqtt.golang 1.5.1
  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20251230T014957-150000.1.134.1

suse advisories SUSE-SU-2026:0037-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

  • influxdb CBL-Mariner 2.0 2.6.1-27
  • influxdb Azure Linux 3.0 2.7.5-10
  • telegraf CBL-Mariner 2.0 1.29.4-18
  • telegraf Azure Linux 3.0 1.31.0-12

azure linux advisories AZL-71299AZL-71311AZL-71320AZL-71332

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-10543 updated cvss 6.5

paho.mqtt.golang: paho.mqtt.golang: Integer Overflow in UTF-8 String Encoding

  • Red Hat Enterprise Linux 7 rhc
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 rhc Red Hat Enterprise Linux 9 rhc Red Hat Enterprise Linux 10 yggdrasil, rhel10/rhel-bootc Red Hat Enterprise Linux AI (RHEL AI) rhelai1/bootc-amd-rhel9, rhelai1/bootc-intel-rhel9, rhelai1/bootc-nvidia-rhel9, rhelai1/bootc-azure-amd-rhel9, rhelai1/bootc-aws-nvidia-rhel9, rhelai1/bootc-gcp-nvidia-rhel9, +1 more Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-aws-cuda-rhel9, rhelai3/bootc-gcp-cuda-rhel9, rhelai3/bootc-azure-cuda-rhel9 Red Hat OpenStack Platform 18.0 rhoso-operators/openstack-rhel9-operator, rhoso-operators/openstack-operator-bundle, rhoso-operators/rabbitmq-cluster-rhel9-operator
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
11 mo ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/eclipse/paho.mqtt.golang
<1.5.1
1.5.1

Affected products

  • Eclipse Foundation paho.mqtt.golang (Go MQTT v3.1 library)

Classification

Weakness
  • CWE-681 Incorrect Conversion between Numeric Types
  • CWE-197 Numeric Truncation Error

References

Sources

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