Description
The tftp_request function in tftp.c in dnsmasq before 2.50, when --enable-tftp is used, allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a TFTP read (aka RRQ) request with a malformed blksize option.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | dnsmasq | 2.50-1 | — |
| Debian 13 | dnsmasq | 2.50-1 | — |
| Debian 12 | dnsmasq | 2.50-1 | — |
| Debian 5.0 | dnsmasq | 2.45-1+lenny1 | DSA-1876-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5 | dnsmasq | 2.45-1.1.el5_3 | RHSA-2009:1238 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- Dnsmasq < 2.50 - Heap Overflow / Null Pointer Dereference EDB-9617 · dos · Sep 9, 2009 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 2
- RHSA-2009:1238 Red Hat Security Advisory: dnsmasq security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DSA-1876-1 dnsmasq - remote code execution Debian Security (DSA / DLA) · Mar 9, 2026
References
- 36563 third-party-advisory
- USN-827-1 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=519020
- 36120 vdb-entry
- http://www.thekelleys.org.uk/dnsmasq/CHANGELOG
- oval:org.mitre.oval:def:9816 vdb-entry signature
- http://www.coresecurity.com/content/dnsmasq-vulnerabilities
- RHSA-2010:0095 vendor-advisory
- RHSA-2009:1238 vendor-advisory