CVE-2023-33657

HIGHNVD 7.57.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2023-06-08. NVD baseline CVSS 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Elevated

Also known asEUVD-2023-37813 (ENISA EUVD) · GHSA-crqc-c8fj-8qjx (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan mitigationThe upstream fix is not in a release yet: until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 1.0%CVSS: 7.5Exploit: No code on recordExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

A use-after-free vulnerability exists in NanoMQ 0.17.2. The vulnerability can be triggered by calling the function nni_mqtt_msg_get_publish_property() in the file mqtt_msg.c. This vulnerability is caused by improper data tracing, and an attacker could exploit it to cause a denial of service attack.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
65
EG Risk 65/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it.
EPSS PROB
1.0%
EPSS %ILE
62nd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
1.0% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

An upstream fix is merged but not yet in a tagged release. Until the release ships, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high, then apply it.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 8, 2023

Last Modified

January 6, 2025

Advisory Details (3)

Auto-updated Nov 5, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
GitHub pull request

Fix data racing on retain msg

Fix merged in emqx/nanomq PR #1187 on 2023-04-20 — awaiting tagged release

https://github.com/emqx/nanomq/pull/1187
Web page

[Security]: wrong protocol name & data racing · Issue #1165 · nanomq/nanomq · GitHub

https://github.com/emqx/nanomq/issues/1165#issue-1668648319
Web page

GitHub - nanomq/nanomq: An ultra-lightweight and blazing-fast Messaging Bus/MQTT Broker for Edge & SDV · GitHub

https://github.com/emqx/nanomq

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 34× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 233 rows on record for this CVE, as 99 entries (1 repeat merged).

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 133 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 00:25 UTCEchelonGraph re-scored
  2. 2026-11-13 00:25 UTCGHSA enrichmentGHSA-crqc-c8fj-8qjx · GitHub severity HIGH · GitHub CVSS 7.5
  3. 2026-11-12 16:30 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  4. 2026-11-11 16:33 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  5. 2026-11-10 16:37 UTCEPSS rescoreEPSS 1.0% · 61st percentile
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  10. 2026-11-05 16:33 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  11. 2026-11-05 11:22 UTCEchelonGraph re-scored
  12. 2026-11-05 11:22 UTCGHSA enrichmentGHSA-crqc-c8fj-8qjx · GitHub severity HIGH · GitHub CVSS 7.5
  13. 2026-11-04 16:31 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  14. 2026-11-03 16:40 UTCEPSS rescoreEPSS 1.0% · 61st percentile
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  19. 2026-10-28 22:19 UTCEchelonGraph re-scored
  20. 2026-10-28 22:19 UTCGHSA enrichmentGHSA-crqc-c8fj-8qjx · GitHub severity HIGH · GitHub CVSS 7.5
  21. 2026-10-28 21:25 UTCOSV refresh
  22. 2026-10-28 16:29 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  23. 2026-10-27 16:29 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  24. 2026-10-26 16:28 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  25. 2026-10-25 17:41 UTCEchelonGraph re-scored
Show 74 more
  1. 2026-10-25 16:29 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  2. 2026-10-24 16:29 UTCEPSS rescoreEPSS 1.0% · 61st percentile
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  5. 2026-10-21 16:29 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  6. 2026-10-21 01:43 UTCEchelonGraph re-scored
  7. 2026-10-21 01:43 UTCGHSA enrichmentGHSA-crqc-c8fj-8qjx · GitHub severity HIGH · GitHub CVSS 7.5
  8. 2026-10-20 16:29 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  9. 2026-10-19 16:29 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  10. 2026-10-18 16:29 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  11. 2026-10-18 07:59 UTCEchelonGraph re-scored
  12. 2026-10-17 16:29 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  13. 2026-10-16 16:35 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  14. 2026-10-15 16:29 UTCEPSS rescoreEPSS 1.0% · 60th percentile
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  16. 2026-10-14 02:24 UTCOSV refresh
  17. 2026-10-13 16:30 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  18. 2026-10-12 18:25 UTCEchelonGraph re-scored
  19. 2026-10-12 16:30 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  20. 2026-10-11 21:52 UTCEchelonGraph re-scored
  21. 2026-10-11 13:45 UTCEPSS rescoreEPSS 1.0% · 60th percentile
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  29. 2026-10-03 14:23 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  30. 2026-09-30 16:24 UTCEchelonGraph re-scored
  31. 2026-09-30 15:01 UTCEPSS rescoreEPSS 1.0% · 60th percentile
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  37. 2026-09-24 14:01 UTCEPSS rescoreEPSS 1.0% · 59th percentile
  38. 2026-09-23 13:45 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  39. 2026-09-23 09:53 UTCOSV refresh
  40. 2026-09-22 14:45 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  41. 2026-09-20 20:14 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  42. 2026-09-16 14:05 UTCEPSS rescoreEPSS 1.0% · 59th percentile
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  53. 2026-09-04 04:46 UTCOSV refresh
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  68. 2026-08-17 15:29 UTCOSV refresh
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Frequently asked(5)

What is CVE-2023-33657?
CVE-2023-33657 is a high-severity vulnerability; its CVE record was published on June 8, 2023. A use-after-free vulnerability exists in NanoMQ 0.17.2. The vulnerability can be triggered by calling the function nni_mqtt_msg_get_publish_property() in the file mqtt_msg.c. This vulnerability is caused by improper data tracing, and an attacker could exploit it to cause a denial of service attack.
When was the CVE record for CVE-2023-33657 published?
The CVE record for CVE-2023-33657 was published on June 8, 2023. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of January 6, 2025; the record at its source may have been updated since.
Is CVE-2023-33657 actively exploited?
CVE-2023-33657 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.0% probability of exploitation in the next 30 days (62nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2023-33657?
CVE-2023-33657 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2023-33657?
An upstream fix for CVE-2023-33657 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2023-33657

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