CVE-2026-93009
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
In dnsmasq, the DHCPv6 client hostname parser can read one byte past the end of a crafted FQDN option because it checks the next label length before confirming the pointer is still inside the option. An attacker on the local network can trigger this with a single DHCPv6 packet. The extra byte is not returned to the client or logged, and no crash has been demonstrated.
Risk Assessment
The vulnerability may lead to an out-of-bounds read, potentially risking data disclosure or service instability. However, no crash or data leak has been demonstrated so far.
Recommendation
Update dnsmasq to a version containing the fix. Until patched, restrict DHCPv6 service access to trusted network segments only.
Other vulnerabilities in dnsmasq
See all- CVE-2026-4893Medium
An information disclosure vulnerability in dnsmasq allows remote attackers to bypass source checks via a crafted DNS packet carrying RFC 7871 client subnet information. The flaw enables circumvention of query origin verification mechanisms.
- CVE-2017-14496High
An integer underflow in the add_pseudoheader function in dnsmasq before version 2.78 allows remote attackers to cause a denial of service via a crafted DNS request when the --add-mac, --add-cpe-id, or --add-subnet option is specified.
- CVE-2017-14495High
A memory leak in dnsmasq before version 2.78 occurs when the --add-mac, --add-cpe-id, or --add-subnet option is specified. This allows remote attackers to cause a denial of service through DNS response creation manipulation.
- CVE-2017-13704High
In dnsmasq before version 2.78, if the DNS packet size does not match the expected size, the size parameter in a memset call gets a negative value. As it is an unsigned value, memset ends up writing up to 0xffffffff zeros, causing dnsmasq to crash.
- CVE-2015-8899High
Dnsmasq before 2.76 allows remote servers to cause a denial of service (crash) via a reply with an empty DNS address that has an (1) A or (2) AAAA record defined locally.
- CVE-2026-4891Medium
A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.
- CVE-2026-4890High
The DNSSEC validation in dnsmasq has a denial of service (DoS) vulnerability. A remote attacker can send a crafted DNS packet, causing the service to crash.
- CVE-2017-14491Critical
Heap-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via a crafted DNS response.
- CVE-2017-14493Critical
A stack-based buffer overflow in dnsmasq before version 2.78 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via a crafted DHCPv6 request.
- CVE-2017-14492Critical
Heap-based buffer overflow in dnsmasq before version 2.78 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via a crafted IPv6 router advertisement request.
Original NVD description (English source)
A flaw was found in dnsmasq. The DHCPv6 client hostname parser can read one byte past the end of a crafted FQDN option because it checks the next label length before confirming the pointer is still inside the option. An attacker on the local network can trigger this with a single DHCPv6 packet. The extra byte is not returned to the client or logged, and no crash has been demonstrated.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS