# CVE-2026-27853: PowerDNS DNSdist out-of-bounds write in changeName Lua methods

Source: https://junglewise.ai/threats/cve-2026-27853-powerdns-dnsdist-out-of-bounds-write-in-changename-lua-methods  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-31. Updated: 2026-07-25  
License: CC BY 4.0 with a link back

CVE-2026-27853 · Severity: medium · CVSS 5.9 · Published 2026-03-31

PowerDNS DNSdist, a load balancer for DNS traffic, is vulnerable to a flaw that can cause the service to crash. An attacker can send specially crafted DNS responses that, when processed by custom scripts, cause the system to attempt to write data outside of its allocated memory. This results in a denial of service, preventing the system from handling legitimate DNS traffic for users and applications.

Technologies: [Powerdns Dnsdist](https://junglewise.ai/threats/technologies/dnsdist). Vendors: [Powerdns](https://junglewise.ai/threats/vendors/powerdns).

## Quick answers

**Is CVE-2026-27853 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-27853 being exploited in the wild.

**How severe is CVE-2026-27853?** Medium severity, with a CVSS score of 5.9, published 31 March 2026.

**Which products and versions are affected?** Powerdns Dnsdist 1.9.0 to 1.9.11, 2.0.0 to 2.0.2.

**Is there a fix for CVE-2026-27853?** A patch was published on 2026-03-31: Fixed versions 1.9.12 and 2.0.3 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-27853 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-27853?** Check whether you run Powerdns Dnsdist at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds write vulnerability (CWE-787) exists in PowerDNS DNSdist when custom Lua code utilizes the DNSQuestion:changeName or DNSResponse:changeName methods. The flaw is triggered when a rewritten DNS packet becomes larger than the initial response and exceeds the 65535-byte limit, causing the DNS packet writer (dnswriter.cc) to write beyond allocated buffers. This is reachable via the network by sending crafted DNS responses to a DNSdist instance configured with these specific Lua methods. The primary impact is a process crash resulting in a denial of service. The issue is fixed in versions 1.9.12 and 2.0.3.

## Affected products

- PowerDNS DNSdist 1.9.0 to 1.9.11, 2.0.0 to 2.0.2

## Timeline

- 2026-03-04: disclosed: Discovery date
- 2026-03-31: advisory: Vendor advisory published
- 2026-03-31: patched: Fixed versions 1.9.12 and 2.0.3 released

## References

- [https://repo.powerdns.com/](https://repo.powerdns.com/)
- [https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-02.html](https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-02.html)

## Related threats

- [PowerDNS DNSdist EDNS options smuggling in EDNS processing](https://junglewise.ai/threats/cve-2026-42004-powerdns-dnsdist-edns-options-smuggling-in-edns-processing)
- [PowerDNS DNSdist denial of service in DNS over HTTP/3](https://junglewise.ai/threats/cve-2026-40211-powerdns-dnsdist-denial-of-service-in-dns-over-http-3)
- [PowerDNS DNSdist out-of-bounds read in SetMacAddrAction](https://junglewise.ai/threats/cve-2026-40210-powerdns-dnsdist-out-of-bounds-read-in-setmacaddraction)
- [PowerDNS DNSdist denial of service via IXFR queries](https://junglewise.ai/threats/cve-2026-40209-powerdns-dnsdist-denial-of-service-via-ixfr-queries)
- [PowerDNS DNSdist denial of service in DoH3 queries](https://junglewise.ai/threats/cve-2026-40208-powerdns-dnsdist-denial-of-service-in-doh3-queries)