CVE-2026-123611 (GCVE-0-2026-123611)

Vulnerability from cvelistv5 – Published: 2026-11-08 01:38 – Updated: 2026-11-08 01:38
VLAI
Title
rustls before 0.23.46 Key Exchange Downgrade via Unauthenticated ServerHello
Summary
rustls before 0.23.46 contains a key exchange downgrade vulnerability that allows network attackers to poison the per-server-name key-exchange group record via an unauthenticated ServerHello. Attackers can answer one connection with a ServerHello selecting X25519, causing later ClientHellos to send only classical shares and lose post-quantum confidentiality.
Severity
6.3 (Medium)
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
3.7 (Low)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE
  • CWE-757 - Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
Assigner
VulnCheck CNA
References
Impacted products
Vendor Product Version
rustls rustls Affected: 0 , < 0.23.46 (semver)
Unaffected: 0.23.46 (semver)
    cpe:2.3:a:rustls_project:rustls:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-10-14 00:00
Credits
Adam010341
Show details on NVD website
To clipboard 

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          "packageURL": "pkg:cargo/rustls",
          "product": "rustls",
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        }
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            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
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            "subConfidentialityImpact": "NONE",
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            "userInteraction": "NONE",
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            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
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      "problemTypes": [
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        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
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      "references": [
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          "name": "GitHub Security Advisory (GHSA-w44r-93j7-qv28)",
          "tags": [
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          ],
          "url": "https://github.com/rustls/rustls/security/advisories/GHSA-w44r-93j7-qv28"
        },
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          "tags": [
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  "cveMetadata": {
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    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-123611",
    "datePublished": "2026-11-08T01:38:36.176Z",
    "dateReserved": "2026-11-06T01:02:39.794Z",
    "dateUpdated": "2026-11-08T01:38:36.176Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}



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