SSRF via missing DNS lookup fallback
Published Jul 31, 2026 · Updated Jul 31, 2026
SSRF in RelunSec dssrf before 1.0.5 allows remote attackers to bypass localhost URL checks when applications use resolver 1.1.1.1. The is_url_safe path accepts localhost as safe after resolve_all_records suppresses DNS resolution failures into empty arrays without falling back to dns.lookup. A consuming application must pass attacker-controlled URLs through this check and then fetch an approved URL; the bypass enables requests to localhost services.
Summary
What happened
SSRF in RelunSec dssrf before 1.0.5 allows remote attackers to bypass localhost URL checks when applications use resolver 1.1.1.1. The is_url_safe path accepts localhost as safe after resolve_all_records suppresses DNS resolution failures into empty arrays without falling back to dns.lookup. A consuming application must pass attacker-controlled URLs through this check and then fetch an approved URL; the bypass enables requests to localhost services.
The record
- CVE
- CVE-2026-54729
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Vendor
- RelunSec
- Product
- dssrf
- Classifications
- CWE-918
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 31, 2026CVE publishedPublication date reported by the CVE source.
- Jul 31, 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=< 1.0.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- GHSA-5846-7qm3-r52j proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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