Cesanta Mongoose mDNS Record mongoose.c handle_mdns_record stack-based overflow
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
A vulnerability was found in Cesanta Mongoose up to 7.20. This impacts the function handle_mdns_record of the file mongoose.c of the component mDNS Record Handler. Performing a manipulation of the argument buf results in stack-based buffer overflow. Remote exploitation of the attack is possible. A high degree of complexity is needed for the attack. The exploitability is said to be difficult. The exploit has been made public and could be used. Upgrading to version 7.21 will fix this issue. The patch is named 0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1. You should upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Cesanta | Mongoose | 7.0; 7.1; 7.2; 7.3; 7.4; 7.5; 7.6; 7.7; 7.8; 7.9; 7.10; 7.11; 7.12; 7.13; 7.14; 7.15; 7.16; 7.17; 7.18; 7.19; 7.20 | 7.21 | Patch available | CNA |
- Mongoose VendorCesanta Affected 7.0; 7.1; 7.2; 7.3; 7.4; 7.5; 7.6; 7.7; 7.8; 7.9; 7.10; 7.11; 7.12; 7.13; 7.14; 7.15; 7.16; 7.17; 7.18; 7.19; 7.20 Fixed in 7.21 Patch available CNA
Remediation
- Fix · CNA Mongoose (Cesanta) Fixed in 7.21
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-5245
- 2026-10-03 Alias added: GHSA-2rqj-7x75-2684
- 2026-10-25 EPSS moved to the 50th–90th percentile
References
More Cesanta Mongoose vulnerabilities
- TI-2026-51393 Mongoose: Content-Length + Transfer-Encoding coexistence enables request smuggling CVSS 3.1CRITICAL 9.1
- TI-2026-51389 Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching CVSS 4.0CRITICAL 9.1
- TI-2023-02723 Cesanta Mongoose MQTT Message Parsing Heap Overflow CVSS 3.1HIGH 8.8
- TI-2020-15865 Buffer overflow in mg_resolve_from_hosts_file in Mongoose 6.18, when reading from a crafted hosts file. CVSS 3.1HIGH 8.8
- TI-2023-17032 The HTTP server in Mongoose before 7.10 accepts requests containing negative… CVSS 3.1HIGH 7.5
- TI-2026-06113 Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop CVSS 4.0MEDIUM 6.9
Sources
- CVE-2026-5245 · CVE Program
- CVE-2026-5245 · NVD
- FIRST EPSS
- GHSA-2rqj-7x75-2684 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-5245 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences