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CVE-2026-4890 is a denial-of-service vulnerability in dnsmasq affecting DNSSEC validation. The flaw is described as an infinite-loop condition, including references to NSEC bitmap parsing during DNSSEC processing. A remote attacker can trigger the vulnerable code path by sending or causing dnsmasq to process a crafted DNS packet, resulting in the daemon becoming stuck while validating DNSSEC data.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository is a dnsmasq vulnerability verification toolkit centered on CVE-2026-2291, CVE-2026-5172, CVE-2026-4890, CVE-2026-4891, CVE-2026-4892, and CVE-2026-4893. It is not tied to a common exploit framework. The repository contains four functional scripts plus documentation: (1) dnsmasq_cve_verify.py is the primary end-to-end black-box verifier that runs from a testing laptop, starts a malicious DNS service, sends trigger traffic to the DUT, and uses SSH to inspect dnsmasq state and logs before issuing PASS/FAIL verdicts; (2) malicious_dns_server.py is a standalone UDP DNS server that returns crafted malformed responses for manual reproduction of selected parser bugs, notably CVE-2026-5172 and DNSSEC-related issues; (3) test_dnsmasq_cve_remote.py is a lightweight remote detection script that queries version.bind over UDP/53 and infers vulnerability status from the reported dnsmasq version; and (4) test_dnsmasq_cve_on_device.sh is a shell-based local checker that runs on the target device and uses version/strings heuristics to assess patch status and feature applicability. The main exploit capability is network-based triggering of dnsmasq parsing flaws through malicious DNS responses. The code crafts malformed CNAME/rdlen combinations, DNSSEC/NSEC/RRSIG-related records, and ECS-related inputs to induce crashes, hangs, or logic bypasses in vulnerable dnsmasq builds. The README also describes a DHCPv6 CLID overflow test for CVE-2026-4892, which is a local/adjacent vector requiring DHCPv6 support and dhcp-script configuration. The repository therefore mixes active exploit-style verification with auxiliary detection scripts. Because payloads are hardcoded and purpose-built for QA verification rather than generalized post-exploitation, the maturity is best classified as OPERATIONAL rather than weaponized. Fingerprintable observables include the default DUT IP 192.168.1.1, example attacker IP 10.0.0.211, SSH on TCP/22, DNS on UDP/53, trigger domains such as crash-5172.evil.test and crash-2291.evil.test, the version.bind CHAOS TXT query, and DUT file paths like /etc/dnsmasq.conf, /tmp/resolv.conf.auto, /sbin/dnsmasq, /usr/sbin/dnsmasq, and /var/log/messages*. Overall, the repository’s purpose is QA/security validation of dnsmasq patch status and exploitability in live devices, especially routers or embedded Linux systems using dnsmasq as a DNS forwarder.
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16 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An upstream dnsmasq vulnerability fixed via backport in OpenWrt's dnsmasq package.
An infinite-loop vulnerability in dnsmasq DNSSEC validation that allows remote denial of service via a crafted DNS packet.
An infinite-loop denial-of-service vulnerability in dnsmasq DNSSEC validation triggered by a crafted DNS packet.
A Dnsmasq DNSSEC-related vulnerability that can be triggered with crafted DNS responses, resulting in service disruption.
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.