Stack overwrite via unchecked DNS record lengths
Published Jan 26, 2026 · Updated Jan 26, 2026
Stack-based buffer overflow in pymumu SmartDNS 47.0 and 47.1 allows remote attackers to corrupt memory via a crafted DNS response. The _dns_decode_rr_head and _dns_decode_SVCB_HTTPS functions trust DNS record lengths without checking them against the bytes remaining in src/dns.c's input buffer. The attacker must influence an upstream SVCB or HTTPS response processed during resolution; successful parsing overwrites stack memory in the DNS service.
Summary
What happened
Stack-based buffer overflow in pymumu SmartDNS 47.0 and 47.1 allows remote attackers to corrupt memory via a crafted DNS response. The _dns_decode_rr_head and _dns_decode_SVCB_HTTPS functions trust DNS record lengths without checking them against the bytes remaining in src/dns.c's input buffer. The attacker must influence an upstream SVCB or HTTPS response processed during resolution; successful parsing overwrites stack memory in the DNS service.
The record
- CVE
- CVE-2026-1425
- Published
- Jan 26, 2026
- Updated
- Jan 26, 2026
- Vendor
- pymumu
- Product
- SmartDNS
- Classifications
- CWE-119, CWE-121, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 26, 2026CVE publishedPublication date reported by the CVE source.
- Jan 26, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=47.0
- Affected versionversion=47.1
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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