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VulnerabilityPublished Updated

CVE-2026-12363: zephyrproject zephyr · Bounds

Affects zephyrproject zephyrSource CVE Database V5

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Not known to be exploited · CVSS 4.2 Medium : upgrade to 4.5.0 or 4.3.2 when convenient.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
4.2Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (zephyr)CVSS 3.14.2
EPSS
0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.5.0, 4.3.2
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade zephyrproject zephyr to 4.5.0 or 4.3.2.

Affected software

ProductAffectedFixed in
zephyrprojectzephyrAffected
  • >=4.4.0 <4.5.0
Fixed in
  • 4.5.0
zephyrprojectzephyrAffected
  • >=3.7.0 <4.3.2
Fixed in
  • 4.3.2
GitHubzephyrpkg:github/zephyrOther threatsAffected
  • >=3.7.0 <4.3.2
  • >=4.4.0 <4.5.0
Fixed in
  • 4.3.2
  • 4.5.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in Zephyr versions 4.3.2 and 4.5.0 that adds a transport-layer check rejecting frag_counter values of zero. Users should upgrade to these or later versions to remediate the vulnerability. No other mitigation is indicated or required.

Description

CVE-2026-12363 is a vulnerability in the Zephyr project's LoRaWAN Fragmented Data Block Transport service where the fragment counter in a received DATA_FRAGMENT command is not validated before use. This can cause an out-of-bounds write to the decoder's internal state, leading to corruption and denial of the firmware update session. Exploitation requires authenticated downlink access and an active fragmentation session. The issue is fixed by rejecting fragment counters with a value of zero.

References

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