Packet of death for DNSCrypt over TCP
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 |
Ubuntu USN |
USN-8946-1 | Unbound vulnerabilities |
Ubuntu USN |
USN-8946-2 | Unbound vulnerabilities |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.293% probability within 30 days)
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Nlnetlabs
Nlnetlabs unbound |
|
| Vendors & Products |
Nlnetlabs
Nlnetlabs unbound |
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat
Redhat hummingbird |
|
| CPEs | cpe:/a:redhat:hummingbird:1 | |
| Vendors & Products |
Redhat
Redhat hummingbird |
|
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In Unbound 1.9.0 up to and including 1.25.1, when a DNSCrypt query is received over TCP, the routine that encrypts the reply in place fails to bound the reply length against the destination buffer size. The size clamp that protects the UDP path is not applied on the TCP path, so a reply larger than 65504 bytes is shifted forward by 48 bytes inside a buffer of capacity equal to 'msg-buffer-size', writing past the end of the heap allocation. A single malicious encrypted query crashes the resolver and lead to denial of service. This vulnerability needs Unbound to be compiled with DNSCrypt support ('--enable-dnscrypt') and the 'dnscrypt:' clause to be configured and enabled for the listening interfaces. | |
| Title | Packet of death for DNSCrypt over TCP | |
| Weaknesses | CWE-122 CWE-787 |
|
| References |
| |
| Metrics |
cvssV3_1
|