CVE-2026-10652 (GCVE-0-2026-10652)
Vulnerability from cvelistv5 – Published: 2026-06-30 15:50 – Updated: 2026-11-04 04:58
VLAI
EPSS
VEX
Title
Out-of-bounds read in Zephyr DNS resolver TXT/SRV record parsing (unvalidated `rdlength`)
Summary
Zephyr's DNS resolver (subsys/net/lib/dns) parses resource records from DNS responses in dns_unpack_answer(), which validated only the fixed RR header (type, class, TTL, rdlength) and accepted any attacker-declared rdlength, including one extending past the end of the received datagram. The TXT and SRV consumers in dns_validate_record() (resolve.c) then read up to rdlength bytes (clamped only to a record-type maximum such as DNS_MAX_TEXT_SIZE, default 64, not to the packet) from the receive buffer via memcpy without their own bounds check, and pass the result to the application's resolve callback. A malicious or spoofed DNS server, an on-path attacker forging UDP DNS replies, or (with mDNS/LLMNR enabled) any LAN node can craft a truncated TXT or SRV response that causes an out-of-bounds read of adjacent receive-pool memory; the disclosed stale bytes (residual contents of prior DNS packets / uninitialized pool memory) are returned to the application as TXT/SRV record contents, an information leak, and may in some configurations cross the allocation boundary and fault, causing a denial of service. The read is bounded (~64 bytes for TXT, ~6 for SRV) and read-only (no write). The fix rejects any record whose declared rdata extends past dns_msg->msg_size at the single chokepoint in dns_unpack_answer(). Affected: v4.3.0 and v4.4.0.
Severity
4.8 (Medium)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-30 16:44 UTC
CWE
- CWE-125 - bounds
Assigner
zephyr
CNA
References
2 references
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| zephyrproject | zephyr |
Affected:
4.3.0 , < 4.3.1
(semver)
Affected: 4.4.0 , < 4.4.1 (semver) |
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