CVE-2026-107836

HIGHPre-NVD 7.17.1
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 7.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (22nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-95931 (ENISA EUVD)Source: ENISA EUVD

7.1EG
EchelonGraph verdictPlan mitigationNo fix is confirmed yet: check with the vendor for a fixed release; until one is applied, restrict network exposure of the affected system on your normal schedule (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.1Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. In 2026.07 and earlier, the nanoCoAP client function nanocoap_sock_get_slice() in sys/net/application_layer/nanocoap/sock.c accepts a Block2 response when _block_cb() sees the expected block number without also verifying that the server-controlled szx and derived offset match the requested block geometry. A malicious CoAP server can return the expected block number with a larger block size, causing the derived offset to exceed the client slice offset and making ctx->offset - offset underflow in _2buf_slice(). The resulting buffer-relative calculation can read before the payload buffer and crash the client, causing denial of service and potentially exposing adjacent memory. No fixed release is available as of this review.

CVSS v3
7.1
EG Score
7.1HIGHmedium confidence
EG Risk
32
EG Risk 32/100

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)
Severity71% × 45%
Impact severity (EG Severity): CVSS 7.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 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: No fix is confirmed yet. Check with the vendor for a fixed release; until one is applied, restrict network exposure of the affected system on your normal schedule.
EPSS PROB
0.3%
EPSS %ILE
22nd
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 (7.1): severity, escalated by confirmed exploitation. This CVE's 7.1 is its impact severity (EG Severity), not escalated.

EG Severity
7.1 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). 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.

No fix is confirmed yet. Check with the vendor for a fixed release; until one is applied, restrict network exposure of the affected system on your normal schedule.

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 9, 2026

Last Modified

October 16, 2026

Advisory Details (3)

Auto-updated Oct 9, 2026
No fix on record yet. Sources: github, github_pr, github_commit.
GitHub commit

commit 49b894cbe091 (RIOT-OS/RIOT)

Fix landed in RIOT-OS/RIOT commit 49b894cbe091 — awaiting tagged release

https://github.com/RIOT-OS/RIOT/commit/49b894cbe091510093273b98d92c4a17167d6839
GitHub pull request

sys/nanocoap: fix handling blockwise transfer

Fix merged in RIOT-OS/RIOT PR #22518 on 2026-08-01 — awaiting tagged release

https://github.com/RIOT-OS/RIOT/pull/22518
GitHub advisoryMentions a patch (unverified)

nanoCoAP Block2 client slice handling underflows on inconsistent server-controlled block size · Advisory · RIOT-OS/RIOT · GitHub

https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-x924-p5fq-26pc

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 37× 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 0.3% · 22nd percentile
  2. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  3. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  4. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  5. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  6. 2026-10-27 20:38 UTCEG score recompute
  7. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  8. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  9. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  10. 2026-10-25 14:54 UTCEG score recompute
  11. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  12. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  13. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  14. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  15. 2026-10-20 19:12 UTCEG score recompute
  16. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  17. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  18. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  19. 2026-10-18 05:07 UTCEG score recompute
  20. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  21. 2026-10-16 17:28 UTCEG score recompute
  22. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  23. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  24. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  25. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
Show 12 more
  1. 2026-10-12 16:38 UTCEG score recompute
  2. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  3. 2026-10-11 20:14 UTCEG score recompute
  4. 2026-10-11 18:26 UTCEG score recompute
  5. 2026-10-11 15:00 UTCEG score recompute
  6. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  7. 2026-10-11 08:08 UTCEG score recompute
  8. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  9. 2026-10-10 06:55 UTCEG score recompute
  10. 2026-10-09 18:19 UTCEG score recompute
  11. 2026-10-09 17:54 UTCEG score recomputeFirst assessed: 7.1 HIGH
  12. 2026-10-09 17:53 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-107836?
CVE-2026-107836 is a high-severity vulnerability; its CVE record was published on October 9, 2026. RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. In 2026.07 and earlier, the nanoCoAP client function nanocoap_sock_get_slice() in sys/net/application_layer/nanocoap/sock.c accepts a Block2 response when _block_cb() sees the…
When was the CVE record for CVE-2026-107836 published?
The CVE record for CVE-2026-107836 was published on October 9, 2026. 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 October 16, 2026; the record at its source may have been updated since.
Is CVE-2026-107836 actively exploited?
CVE-2026-107836 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (22nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-107836?
CVE-2026-107836 has a CVSS base score of 7.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-107836?
No fix for CVE-2026-107836 is confirmed yet. Until one is published, restrict network exposure of the affected system — for example, keep it off the internet or limit it to trusted networks — and watch for a fix.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-107836

Explore →

Is Your Infrastructure Affected by CVE-2026-107836?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.