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Fencer Vulns
low 3.7

CVE-2026-2966 json

Cesanta Mongoose DNS Transaction ID dns.c mg_sendnsreq random values

published 2026-02-23 8 mo ago modified 2026-07-25 3 mo ago also EUVD-2026-7602 , GHSA-m5mm-h952-fxjj , JLSEC-2026-366

cvss
3.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

A weakness has been identified in Cesanta Mongoose up to 7.20. The impacted element is the function mg_sendnsreq of the file /src/dns.c of the component DNS Transaction ID Handler. Executing a manipulation of the argument random can lead to insufficiently random values. The attack can be launched remotely. The attack requires a high level of complexity. The exploitability is regarded as difficult. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Patch / fix

  • julia Mongoose_jll 7.21.0+0
  • swupdate Debian 14 2025.12+dfsg-10

debian advisories DEBIAN-CVE-2026-2966

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-2966 updated cvss 3.7

Mongoose: Mongoose: Information disclosure due to insufficiently random values in DNS transaction ID handling

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
8 mo ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/dwBruijn/CVEs/blob/main/Mongoose/mg_sendnsreq.md#poc referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/dwBruijn/CVEs/blob/main/Mongoose/mg_sendnsreq.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
CNA 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R
CNA 3.0 3.7 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:X/RC:R
CNA 2.0 2.6 AV:N/AC:H/Au:N/C:N/I:P/A:N/E:POC/RL:ND/RC:UR
CNA 4.0 2.9 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CNA 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CNA 2.0 2.6 AV:N/AC:H/Au:N/C:N/I:P/A:N
OSV 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
julia Mongoose_jll
<7.21.0+0
7.21.0+0

Affected products

  • Cesanta Mongoose

Classification

Weakness
  • CWE-330 Use of Insufficiently Random Values
  • CWE-310 Cryptographic Issues

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.