Integer overflow in Hickory-Dns
CVE-2026-123571
Hickory DNS from 0.26.0 before 0.26.2 contains an integer underflow vulnerability in TSIG RDATA decoding that allows remote attackers to trigger a panic via malformed records. Attackers can send a crafted TSIG record in DNS wire format to cause unchecked subtraction underflow, crashing builds with overflow checks enabled and causing denial of service.
Published .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (35.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
The 30-day trend appears once there are two daily scores.
Affected products
Weakness classification (CWE)
References
- github.com/hickory-dns/hickory-dns/security/advisories/GHSA-x962-5xwx-fr8x (vendor-advisory)
- www.vulncheck.com/advisories/hickory-dns-from-0.26.0-before-0.26.2-panic-via-ts… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123571?
- CVE-2026-123571 is a high-severity vulnerability in Hickory-Dns, classified under Integer Underflow. CVSS score: 7.5/10. Published 2026-11-08.
- How severe is CVE-2026-123571?
- High severity. CVSS v3 base score is 7.5 out of 10.