CMS key-transport recipient key-size validation never runs for RFC 9709 HKDF-derived keys
CVSS Skor
6.9
EPSS İhtimal
%0.2
Risk Skoru
0.0
Yayın
9 gün önce
Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.
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Zafiyet Açıklaması
DayBreach CVE AI Araştırması
CVE-2026-71892 için toplanan üretici, dağıtım, yama ve güvenlik kaynağı kayıtlarını karşılaştırıp kanıt bağlantılı bir açıklama hazırlayalım.
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-size lookup on the outer wrapper OID. That OID identifies a key-derivation construction rather than a cipher and has no registered key size, so the size comparison was skipped entirely. A key-transport EnvelopedData or AuthEnvelopedData whose transported, HKDF-derived content-encryption key did not match the key size of the advertised content-encryption algorithm was therefore accepted even with validation explicitly enabled, silently defeating the only mechanism the API offers for enforcing recovered key size. The recipient now dispatches on the content-encryption AlgorithmIdentifier's algorithm OID, so validation checks the recovered key against the inner content-encryption algorithm. Messages with a matching key size, non-HKDF messages, and recipients that do not enable validation are unaffected. This issue also affects Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).
IMPACT — Etkilenen Ürünler ve Yazılımlar
Affected Products
The following products are affected by CVE-2026-71892 vulnerability. Even if our threat engine is aware of the exact versions of the products that are affected, the information is represented below.
RED HAT CSAF/VEX — Ürün Etki Kontrolü
SCORING — CVSS Çoklu Kaynak Skoru
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from various sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 6.9 | CVSS V4_0 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/U:Amber | CVE CNA |
| 6.9 | CVSS V40 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/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:Amber | NVD |
Yama ve İyileştirme Rehberi (Solution)
Solution & Remediation Advisory
2 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.
Public exploit ve aktif sömürü durumu
Doğrulanmış exploit istihbaratı
Bu CVE için henüz doğrulanmış public PoC, exploit repository’si veya Metasploit modülü bulunamadı.
Zafiyet Dağılımı ve Saldırı Kalıpları (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-71892 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-71892 weaknesses.
Saldırı Vektörü ve Erişilebilirlik Karakteristiği
Resmi Kaynaklar ve Danışma Bültenleri
CVSS Vektör Radar Grafiği
6.9 / 10Vulnerability Scoring Details
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/U:AmberYama doğrulandı
Zafiyet Türü (CWE & CAPEC)
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curl -H "x-api-key: $DAYBREACH_API_KEY" \ "https://api.enginteksut.com.tr/api/v1/intel/cves/CVE-2026-71892"