Detections
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Echo: unbound: security update to 1.25.2

medium Tenable Self-Hosted Container Security Plugin ID 461000

Description

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

 - In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA
 form for an RRSIG-covered PX/RP/MINFO/SOA RRset, it computes the address of the second embedded domain
 name as 'datstart + dname_valid(datstart, ...)' and passes it straight to 'query_dname_tolower()' without
 checking that a second name is actually present in the RDATA. The wire-format parser accepts multi-dname
 RRs whose RDATA ends after the first name, so an attacker who runs a DNSSEC-signed authoritative server
 can deliver a record with an absent second domain name (e.g. SOA record) and cause 'query_dname_tolower()'
 to walk label-by-label through stale bytes in the per-worker 'env->scratch_buffer', past the end of that
 heap allocation if 'msg-buffer-size' has been lowered from the default. This leads to heap buffer overflow
 and on a release build the outcome relies heavily on the contents of the buffer tail and the adjacent heap
 chunk. (CVE-2026-56416)

Solution

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

See Also

https://advisory.echohq.com/cve/CVE-2026-56416

Plugin Details

Severity: Medium

ID: 461000

Version: Revision 1.2

Type: Local

Published: 10/2/2026

Updated: 10/5/2026

Supported Sensors: Tenable Cloud Security, Tenable Self-Hosted Container Security

Risk Information

VPR

Risk Factor: Low

Score: 2.1

Percentile: 8.1

CVSS v2

Risk Factor: Medium

Base Score: 4

Temporal Score: 3

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

CVSS Score Source: CVE-2026-56416

CVSS v3

Risk Factor: Medium

Base Score: 4.8

Temporal Score: 4.2

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/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-2026-56416