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VulnerabilityPublished Updated

CVE-2026-8718: zephyrproject zephyr · Bounds

Affects zephyrproject zephyrSource CVE Database V5

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Not known to be exploited · CVSS 8.4 High : upgrade to 4.4.1 or 4.3.2 soon.

Data as of 8 Nov 2026, 23:24 UTC

CVSS 3.1 base score
8.4High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (zephyr)CVSS 3.18.4
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.4.1, 4.3.2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 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 8 Nov 2026.

What to do

Upgrade zephyrproject zephyr to 4.4.1 or 4.3.2.

Affected software

ProductAffectedFixed in
zephyrprojectzephyrAffected
  • >=4.4.0 <4.4.1
Fixed in
  • 4.4.1
zephyrprojectzephyrAffected
  • >=3.5.0 <4.3.2
Fixed in
  • 4.3.2
GitHubzephyrpkg:github/zephyrOther threatsAffected
  • >=3.5.0 <4.3.2
  • >=4.4.0 <4.4.1
Fixed in
  • 4.3.2
  • 4.4.1

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

AI-suggested

The described fix rejects calls with optlen smaller than MBEDTLS_SSL_CID_OUT_LEN_MAX, returning -EINVAL. Until an official fix is confirmed, avoid enabling CONFIG_MBEDTLS_SSL_DTLS_CONNECTION_ID or restrict unprivileged user access to DTLS sockets. Monitor vendor channels for patch releases and apply updates promptly once available.

Description

tls_opt_dtls_peer_connection_id_value_get() in subsys/net/lib/sockets/sockets_tls.c, which handles getsockopt(SOL_TLS, TLS_DTLS_PEER_CID_VALUE), passed the caller-supplied optval directly to mbedtls_ssl_get_peer_cid() without verifying the buffer was at least MBEDTLS_SSL_CID_OUT_LEN_MAX (default 32) bytes. mbedtls_ssl_get_peer_cid() copies the peer-negotiated DTLS Connection ID (length 1..MBEDTLS_SSL_CID_OUT_LEN_MAX) into that buffer without a destination-size parameter, so a caller-supplied optlen smaller than the CID causes a write of up to 31 bytes past the buffer end. In CONFIG_USERSPACE builds the getsockopt syscall verifier (z_vrfy_zsock_getsockopt) bounce-buffers the user's optval into a kernel allocation of exactly optlen bytes (k_usermode_alloc_from_copy -> z_thread_malloc), so an unprivileged user thread that passes a small optlen on a connected DTLS socket with Connection ID enabled induces a kernel-heap buffer overflow, with the overflowing content being the remote peer's CID. The defect requires CONFIG_MBEDTLS_SSL_DTLS_CONNECTION_ID, an established DTLS session with a negotiated peer CID, and (for the kernel-crossing case) CONFIG_USERSPACE. Introduced when the TLS_DTLS_CID option was added (v3.5.0). The fix rejects callers whose optlen is below MBEDTLS_SSL_CID_OUT_LEN_MAX with -EINVAL.

References

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