Loading vulnerability…
CVE-2026-5857 is a memory corruption vulnerability in the Contiki-NG MQTT client in parse_publish_vhdr() within os/net/app-layer/mqtt/mqtt.c. The flaw arises because the parser sets the internal state flag indicating that the topic length has been received before validating that length against the 64-byte limit. If an over-length MQTT topic is encountered, the function returns early but leaves that state flag set. When parsing resumes on a subsequent TCP segment, the persisted state causes the code path containing the topic-length bounds check to be skipped, and execution falls through to a memcpy() that uses the previously supplied unvalidated 16-bit topic length as the copy size. This permits overflow of the 65-byte topic buffer into adjacent structure fields, including a pointer later used by MQTT processing, creating a memory corruption condition that can be leveraged by a compromised or attacker-controlled broker. The issue is remotely reachable over the MQTT connection, which is plaintext because the implementation does not support TLS.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.