Is CVE-2026-49140 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-49140 being exploited in the wild.

How severe is CVE-2026-49140?

Medium severity, with a CVSS score of 4.3, published 1 June 2026.

Is there a fix for CVE-2026-49140?

A patch was published on 2026-05-30: Pull request merged to harden Matrix media handling Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-49140 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-49140?

Check whether you run HKUDS Nanobot at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-49140: HKUDS Nanobot denial of service in Matrix media download handler

CVE-2026-49140 · Severity: medium · CVSS 4.3 · Published 2026-06-01

Nanobot, an AI agent framework, contains a flaw in how it handles media files sent through the Matrix messaging platform. An authorized user in a chat room can send specially crafted media files that lack size information, forcing the bot to download and store the entire file in memory before checking if it is too large. This can be used to crash the bot or slow down its operations by exhausting its memory and internet bandwidth.

Technologies: HKUDS Nanobot. Vendors: HKUDS.

Quick answers

Is CVE-2026-49140 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-49140 being exploited in the wild.
How severe is CVE-2026-49140?: Medium severity, with a CVSS score of 4.3, published 1 June 2026.
Which products and versions are affected?: HKUDS Nanobot < 0.2.1.
Is there a fix for CVE-2026-49140?: A patch was published on 2026-05-30: Pull request merged to harden Matrix media handling Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-49140 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-49140?: Check whether you run HKUDS Nanobot at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A denial of service vulnerability exists in Nanobot's Matrix channel media download handler due to improper resource allocation (CWE-770). The handler previously only validated file sizes if the 'info.size' metadata was present in the Matrix media event; if missing or invalid, the bot would proceed to fully materialize the response body in memory before performing a post-download size check. An authenticated attacker (a member of a Matrix room the bot processes) can send multiple concurrent media events with omitted size metadata to trigger simultaneous large downloads. This leads to process memory exhaustion and bandwidth saturation. The vulnerability is fixed in version 0.2.1 by implementing early rejection of missing size metadata, streaming downloads with a hard byte cap, and limiting concurrent downloads via a semaphore.

Affected products

HKUDS Nanobot < 0.2.1

Timeline

2026-05-30: patched: Pull request merged to harden Matrix media handling
2026-06-01: advisory: NVD and VulnCheck published advisory details

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.