DNS Cookie bypass when combined with proxy-protocol use
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| NLnet Labs | Unbound | unaffected |
|
| Package | CPE | Advisory | Released Date |
|---|---|---|---|
| Red Hat Hardened Images | |||
| unbound-main-1.25.2-0.1.hum1 | cpe:/a:redhat:hummingbird:1 | RHSA-2026:43588 | 2026-07-22T00:00:00Z |
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Nlnetlabs | Unbound |
|
Vendor Solution
This issue is fixed starting with version 1.25.2
| Source | ID | Title |
|---|---|---|
Debian DSA |
DSA-6507-1 | unbound security update |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.241% probability within 30 days)
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat
Redhat hummingbird |
|
| Weaknesses | CWE-303 | |
| CPEs | cpe:/a:redhat:hummingbird:1 | |
| Vendors & Products |
Redhat
Redhat hummingbird |
|
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Nlnetlabs
Nlnetlabs unbound |
|
| Vendors & Products |
Nlnetlabs
Nlnetlabs unbound |
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In NLnet Labs Unbound 1.18.0 up to and including 1.25.1, when Unbound listens on a 'proxy-protocol-port' interface with 'answer-cookie: yes', the RFC 9018 server-cookie SipHash is computed over the proxy's wire address instead of the PROXYv2-declared client. One server cookie obtained through a given proxy node therefore validates for every PROXYv2-declared source behind that node. On a UDP+proxy-protocol front, an off-path attacker can harvest one cookie with a single legitimate query, then replay it under any spoofed source and pass DNS Cookie checks that were deployed to defeat this in the first place. | |
| Title | DNS Cookie bypass when combined with proxy-protocol use | |
| Weaknesses | CWE-290 | |
| References |
| |
| Metrics |
cvssV3_1
|