CVE-2026-107836

HIGHPre-NVD 7.17.1
EchelonGraph scoreLOW confidence

This high-severity CVE scores 7.1 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: cna:github_m
7.1EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: —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
7.1HIGHlow confidence
EG Risk
32
EG Risk 32/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity71% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
EPSS PROB
—
EPSS %ILE
—
KEV
Not listed

CISA SSVCTrack at every mission impact level.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 9, 2026

Last Modified

October 9, 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_pr

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
githubMentions 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 3× in last 7d / 3× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-10-09 18:19 UTCEG score recompute
  2. 2026-10-09 17:54 UTCEG score recompute
  3. 2026-10-09 17:53 UTCMITRE cvelistV5first tracked

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Frequently asked(4)

What is CVE-2026-107836?
CVE-2026-107836 is a high vulnerability 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 nanocoapsockgetslice() in sys/net/applicationlayer/nanocoap/sock.c accepts a Block2 response when blockcb() sees the…
When was CVE-2026-107836 disclosed?
CVE-2026-107836 was first published on October 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
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). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
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 or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix.

Dependency Blast Radius

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