Detections
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Echo: unbound: security update to 1.25.2

low Tenable Cloud Security Plugin ID 464239

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, client terminated DNS-over-QUIC (DoQ) queries are
 not accounted properly by Unbound resulting in low-cost inflation of the waiting number of replies for
 already in-flight resolution queries. This results in degradation of resolution service for new clients
 for already in-flight queries. A malicious actor can exploit the vulnerability by issuing DoQ queries for
 query names that need resolution and proceeding on immediately terminating the query by one of
 STOP_SENDING/RESET_STREAM/CONNECTION_CLOSE QUIC frames. Those terminated DoQ queries are not properly
 counted for and keep inflating the number of waiting replies for in-flight queries. When the maximum is
 reached, it results in silent query drops for new clients needing resolution for already in-flight
 queries. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the
 'quic-port' to be configured for the listening interfaces. Additionally, a malicious actor needs access to
 multiple source IPs to bypass the by-default configured 'wait-limit' option. (CVE-2026-41637)

Solution

Update the unbound library and its related packages to version 1.25.2 or later.

See Also

https://advisory.echohq.com/cve/CVE-2026-41637

Plugin Details

Severity: Low

ID: 464239

Version: Revision 1.1

Type: Local

Published: 10/2/2026

Updated: 10/2/2026

Risk Information

VPR

Risk Factor: Low

Score: 1.2

Percentile: 0.01

CVSS v2

Risk Factor: Low

Base Score: 2.6

Temporal Score: 1.9

Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2026-41637

CVSS v3

Risk Factor: Low

Base Score: 3.7

Temporal Score: 3.2

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 7/23/2026

Vulnerability Publication Date: 7/22/2026

Reference Information

CVE: CVE-2026-41637