CVE-2026-19937

MEDIUMPre-NVD 5.75.7
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 5.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (7th 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
Trending — 3 sources updated this week
5.7EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.7Exploit: None knownExposed services: Not assessed

A fix is referenced (a reference tagged "Patch", often a source commit), but no release containing it is confirmed — find the release that contains it; until it is applied, mitigate (WAF / firewall / segmentation).

The Bluetooth Mesh Access layer delayable-message machinery in subsys/bluetooth/mesh/delayable_msg.c manages a static pool of CONFIG_BT_MESH_ACCESS_DELAYABLE_MSG_COUNT message contexts (default 4) threaded onto a free_ctx or busy_ctx list. release_delayable_msg_ctx() returned a context to free_ctx only when sys_slist_find_and_remove() found it on busy_ctx. The chunk-exhaustion error path in bt_mesh_delayable_msg_manage() releases a context that was already popped off free_ctx but not yet inserted on busy_ctx, so the context was appended to neither list and was permanently lost from the pool. Because bt_mesh_delayable_msg_init() runs only once from bt_mesh_init(), and node reset/suspend only drain busy_ctx, the loss survives unprovision, re-provision and suspend/resume — it is cleared only by a reboot.

The error path is reached when the chunk pool (CONFIG_BT_MESH_ACCESS_DELAYABLE_MSG_CHUNK_COUNT, default 40 chunks) is short of the chunks a new delayed message needs and the oldest pending message cannot be flushed because bt_mesh_access_send() returns -EBUSY or -ENOBUFS (all segmented-TX contexts busy, or advertising/segment buffers exhausted). A peer that is provisioned into the mesh network — holding a valid NetKey plus an AppKey or DevKey bound to a server model — can drive both conditions by flooding the victim with requests that elicit segmented responses while withholding the Segment Acknowledgment, which keeps the transmit contexts occupied while queued responses hold the chunk pool. Each further request that arrives in that window leaks one context.

Once the pool is drained, bt_mesh_delayable_msg_manage() returns -ENOMEM for every subsequent send and bt_mesh_model_send() propagates that error with no fallback to an immediate transmit. Since CONFIG_BT_MESH_ACCESS_DELAYABLE_MSG and CONFIG_BT_MESH_ACCESS_DELAYABLE_MSG_CTX_ENABLED are both enabled by default, ctx->rnd_delay is set for every received access message, so all replies from Configuration Server, Health Server and application server models are silently dropped. The node keeps receiving and processing traffic but never answers, a persistent denial of service until the device is restarted. There is no memory corruption, information disclosure or integrity impact; releases before the fix compute the chunk count from the transmit buffer capacity rather than its payload length, making chunk-pool starvation — and therefore the leak — considerably easier to provoke.

CVSS v3
5.7
EG Score
5.7MEDIUMmedium confidence
EG Risk
26
EG Risk 26/100

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 (value × EchelonGraph’s weight)
Severity57% × 45%
The EG Score, 5.7 of 10.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines; until then, restrict network exposure of the affected system or apply the vendor's mitigation.
EPSS PROB
0.2%
EPSS %ILE
7th
KEV
Not listed

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

A fix is referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines; until then, restrict network exposure of the affected system or apply the vendor's mitigation.

Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” 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 13, 2026

Advisory Details (2)

Auto-updated Oct 12, 2026
Fix referenced — no release confirmed yet. Sources: github_commit, github.
GitHub advisoryMentions a patch (unverified)

Bluetooth Mesh Access layer permanently leaks delayable-message contexts, disabling all model responses · Advisory · zephyrproject-rtos/zephyr · GitHub

https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-5rrx-xww6-5xrh
GitHub commit

commit 097001f187ba (zephyrproject-rtos/zephyr)

Fix landed in zephyrproject-rtos/zephyr commit 097001f187ba — awaiting tagged release

https://github.com/zephyrproject-rtos/zephyr/commit/097001f187ba2764e9ef1cc7113b8da525bf741c

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 5× 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. 2026-10-13 17:10 UTCEG score recompute
  2. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
  3. 2026-10-13 00:27 UTCEG score recompute
  4. 2026-10-12 23:26 UTCEG score recomputeFirst assessed: 5.7 MEDIUM
  5. 2026-10-12 23:24 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-19937?
CVE-2026-19937 is a medium-severity vulnerability; its CVE record was published on October 12, 2026. The Bluetooth Mesh Access layer delayable-message machinery in subsys/bluetooth/mesh/delayablemsg.c manages a static pool of CONFIGBTMESHACCESSDELAYABLEMSGCOUNT message contexts (default 4) threaded onto a freectx or busyctx list. releasedelayablemsgctx() returned a context to freectx only when…
When was the CVE record for CVE-2026-19937 published?
The CVE record for CVE-2026-19937 was published on October 12, 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 13, 2026; the record at its source may have been updated since.
Is CVE-2026-19937 actively exploited?
CVE-2026-19937 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (7th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-19937?
CVE-2026-19937 has a CVSS base score of 5.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-19937?
A fix for CVE-2026-19937 is referenced (a reference tagged "Patch", often a source commit), but EchelonGraph has no release containing it on record. Check that reference and the vendor's advisory for a release that contains the fix and update to it; until then, restrict network exposure of the affected system or apply the vendor's mitigation.

Dependency Blast Radius

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