CVE-2026-77972 json
safeurl validated address is not bound to the request, allowing DNS rebinding
published 2026-09-15 54 d ago modified 2026-09-21 48 d ago also EEF-CVE-2026-77972 , EUVD-2026-78676
- cvss
- 9.0
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 26%
- public exploits
- 0
- none known
Summary
Time-of-check Time-of-use (TOCTOU) Race Condition in Slab safeurl allows an attacker who controls a hostname's DNS responses to reach internal network destinations that validation rejected.
Validation returns a verdict and not the address it approved, so the HTTP clients the library ships receive the original hostname and resolve it a second time when the request is made. An attacker who controls the authoritative DNS for a name can answer the first lookup with a permitted address and the second with a blocked one, and the request then reaches a destination validation never approved. The same window opens without an attacker whenever a name legitimately resolves to different addresses across lookups, such as short record lifetimes or rotation between several addresses.
This issue affects safeurl: from 0.1.0 onward.
Patch / fix
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 48 d ago
Exploit prediction
0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.0 | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N |
| CNA | 4.0 | 9.0 | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| hex | safeurl | >=0.1.0 |
no fix listed |
Affected products
- Slab safeurl
Classification
- Weakness
-
- CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
References
-
github.com
/slab/safeurl-elixir/commit/feabbd0a13f83028ab24b71710526e9da9841f70
related, web
-
cna.erlef.org
/cves/CVE-2026-77972.html
related, third-party-advisory, web
-
osv.dev
/vulnerability/EEF-CVE-2026-77972
related
-
hex.pm
/packages/safeurl
package
Sources
- CVE List CVE-2026-77972
- NVD CVE-2026-77972
- OSV EEF-CVE-2026-77972
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