CVE-2026-108952

MEDIUMPre-NVD 4.64.6
EchelonGraph scoreHIGH confidence

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

Score 4.6 from GitHub Security Advisory published 2026-10-12. A secondary CVSS source baseline 4.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this week

Also known asEUVD-2026-97359 (ENISA EUVD) · GHSA-x4hq-c3c6-m368 (GitHub Security Advisories)Source: ENISA EUVD

4.6EG
EchelonGraph verdictMonitorThe 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, then apply it (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 4.6Exploit: None knownExposed services: Not assessed

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

RT-Thread through 5.3.0 contains a memory corruption vulnerability in the legacy USB CDC virtual COM port driver that aliases rx_ringbuffer as a Serial V2 rt_serial_rx_fifo in _function_enable(). A connected USB host configuring the CDC device triggers writes past the ring buffer into struct vcom members and an invalid rt_free() on close, causing denial of service.

CVSS v3
4.6
EG Score
4.6MEDIUMhigh confidence
EG Risk
21
EG Risk 21/100

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)
Severity46% × 45%
Impact severity (EG Severity): CVSS 4.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (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, then apply it.
EPSS PROB
0.2%
EPSS %ILE
9th
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 (4.6): severity, escalated by confirmed exploitation. This CVE's 4.6 is its impact severity (EG Severity), not escalated.

EG Severity
4.6 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-28). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.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 every mission impact level.

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, then apply it.

Exploitation none (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade 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. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (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

October 12, 2026

Last Modified

October 16, 2026

Advisory Details (6)

Auto-updated Oct 12, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr, github_commit.
Web page

RT-Thread through 5.3.0 Memory Corruption via USB CDC VCOM Driver | Advisories | VulnCheck

https://www.vulncheck.com/advisories/rt-thread-through-5.3.0-memory-corruption-via-usb-cdc-vcom-driver
Web page

GitHub - RT-Thread/rt-thread: RT-Thread is an open source IoT Real-Time Operating System (RTOS). https://rt-thread.github.io/rt-thread/ · GitHub

https://github.com/RT-Thread/rt-thread
Web page

rt-thread/components/legacy/usb/usbdevice/class/cdc_vcom.c at 99428a1e7f7447955aa860f7c969273a12095b8f · RT-Thread/rt-thread · GitHub

https://github.com/RT-Thread/rt-thread/blob/99428a1e7f7447955aa860f7c969273a12095b8f/components/legacy/usb/usbdevice/class/cdc_vcom.c#L518
GitHub commit

commit ceef6e0ccd64 (RT-Thread/rt-thread)

Fix landed in RT-Thread/rt-thread commit ceef6e0ccd64 — awaiting tagged release

https://github.com/RT-Thread/rt-thread/commit/ceef6e0ccd646aef61b907aeb9f29269d1caba50
GitHub pull request

fix[usb]: stop aliasing rt_ringbuffer as rt_serial_rx_fifo in VCOM

Fix merged in RT-Thread/rt-thread PR #11770 on 2026-10-11 — awaiting tagged release

https://github.com/RT-Thread/rt-thread/pull/11770
Web page

[Bug] Legacy USB CDC VCOM uses rt_ringbuffer as rt_serial_rx_fifo with Serial V2 · Issue #11739 · RT-Thread/rt-thread · GitHub

https://github.com/RT-Thread/rt-thread/issues/11739

Vendor Advisories for CVE-2026-108952(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 35× 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 it from the CNA feed. 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). Most recent first.

  1. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  2. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  3. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  4. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  5. 2026-10-29 15:01 UTCEG score recompute
  6. 2026-10-29 15:01 UTCGHSA enrichmentGHSA-x4hq-c3c6-m368 · GitHub CVSS 4.6
  7. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  8. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  9. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  10. 2026-10-25 14:53 UTCEG score recompute
  11. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  12. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  13. 2026-10-23 08:19 UTCEG score recompute
  14. 2026-10-23 08:18 UTCGHSA enrichmentGHSA-x4hq-c3c6-m368 · GitHub CVSS 4.6
  15. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  16. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  17. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  18. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  19. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  20. 2026-10-18 05:07 UTCEG score recompute
  21. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  22. 2026-10-16 19:43 UTCEG score recompute
  23. 2026-10-16 19:43 UTCGHSA enrichmentGHSA-x4hq-c3c6-m368 · GitHub CVSS 4.6
  24. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  25. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
Show 10 more
  1. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  2. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  3. 2026-10-13 15:29 UTCEG score recompute
  4. 2026-10-13 15:29 UTCGHSA enrichmentGHSA-x4hq-c3c6-m368 · GitHub CVSS 4.6
  5. 2026-10-13 15:07 UTCEG score recompute
  6. 2026-10-13 15:07 UTCGHSA enrichmentGHSA-x4hq-c3c6-m368 · GitHub CVSS 4.6
  7. 2026-10-12 16:38 UTCEG score recompute
  8. 2026-10-12 13:26 UTCEG score recompute
  9. 2026-10-12 12:32 UTCEG score recomputeFirst assessed: 4.6 MEDIUM
  10. 2026-10-12 12:31 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-108952?
CVE-2026-108952 is a medium-severity vulnerability; its CVE record was published on October 12, 2026. RT-Thread through 5.3.0 contains a memory corruption vulnerability in the legacy USB CDC virtual COM port driver that aliases rx_ringbuffer as a Serial V2 rt_serial_rx_fifo in _function_enable(). A connected USB host configuring the CDC device triggers writes past the ring buffer into struct vcom…
When was CVE-2026-108952 made public?
CVE-2026-108952 was made public on August 23, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on October 12, 2026. EchelonGraph's copy of the record carries a last-modified date of October 16, 2026; the record at its source may have been updated since.
Is CVE-2026-108952 actively exploited?
CVE-2026-108952 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (9th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-108952?
CVE-2026-108952 has a CVSS base score of 4.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-108952?
An upstream fix for CVE-2026-108952 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. The vendor advisories EchelonGraph has for CVE-2026-108952 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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