GHSA-gx3x-vq4p-mhhv cert-manager-controller DoS via Specially Crafted DNS Response

• Go github.com/cert-manager/cert-manager: >= 1.18.0, < 1.18.5 → fixed in 1.18.5 • Go github.com/cert-manager/cert-manager: >= 1.19.0, < 1.19.3 → fixed in 1.19.3

Impact The cert-manager-controller performs DNS lookups during ACME DNS-01 processing (for zone discovery and propagation self-checks). By default, these lookups use standard unencrypted DNS. An attacker who can intercept and modify DNS traffic from the cert-manager-controller pod can insert a crafted entry into cert-manager's DNS cache. Accessing this entry will trigger a panic, resulting in Denial of Service (DoS) of the cert-manager controller. The issue can also be exploited if the authoritative DNS server for the domain being validated is controlled by a malicious actor. Patches The vulnerability was introduced in cert-manager v1.18.0 and has been patched in cert-manager v1.19.3 and v1.18.5, which are the supported minor releases at the time of publishing. cert-manager versions prior to v1.18.0 are unaffected. Workarounds • Using DNS-over-HTTPS reduces the risk of DNS traffic being intercepted and modified. • Note that DNS-over-HTTPS does *not* prevent the risk of an attacker-controlled authoritative DNS server. Resources • Fix for cert-manager 1.18: https://github.com/cert-manager/cert-manager/pull/8467 • Fix for cert-manager 1.19: https://github.com/cert-manager/cert-manager/pull/8468 • Fix for master branch: https://github.com/cert-manager/cert-manager/pull/8469 Credits Huge thanks to Oleh Konko (@1seal) for reporting the issue, providing a detailed PoC and an initial patch!