Vulnerability Description
OpenWrt Project is a Linux operating system targeting embedded devices. In versions prior to 24.10.6 and 25.12.1, the mdns daemon has a Stack-based Buffer Overflow vulnerability in the parse_question function. The issue is triggered by PTR queries for reverse DNS domains (.in-addr.arpa and .ip6.arpa). DNS packets received on UDP port 5353 are expanded by dn_expand into an 8096-byte global buffer (name_buffer), which is then copied via an unbounded strcpy into a fixed 256-byte stack buffer when handling TYPE_PTR queries. The overflow is possible because dn_expand converts non-printable ASCII bytes (e.g., 0x01) into multi-character octal representations (e.g., \001), significantly inflating the expanded name beyond the stack buffer's capacity. A crafted DNS packet can exploit this expansion behavior to overflow the stack buffer, making the vulnerability reachable through normal multicast DNS packet processing. This issue has been fixed in versions 24.10.6 and 25.12.1.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Openwrt | Openwrt | < 24.10.6 |
Related Weaknesses (CWE)
References
- https://github.com/openwrt/openwrt/releases/tag/v24.10.6Release Notes
- https://github.com/openwrt/openwrt/releases/tag/v25.12.1Release Notes
- https://github.com/openwrt/openwrt/security/advisories/GHSA-7c3j-f7w2-p8f6Vendor Advisory
FAQ
What is CVE-2026-30871?
CVE-2026-30871 is a vulnerability with a CVSS score of 9.8 (CRITICAL). OpenWrt Project is a Linux operating system targeting embedded devices. In versions prior to 24.10.6 and 25.12.1, the mdns daemon has a Stack-based Buffer Overflow vulnerability in the parse_question ...
How severe is CVE-2026-30871?
CVE-2026-30871 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-30871?
Check the references section above for vendor advisories and patch information. Affected products include: Openwrt Openwrt.