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CVE-2026-50722— IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload

Quick assessment

Affected
The Libreswan Project libreswan
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Libreswan是Libreswan团队开源的一个IPsec实现。 libreswan 5.3及之前版本存在加密问题漏洞，该漏洞源于函数RSA_authenticate_hash_signature_pkcs1_1_5_rsa()未能正确验证IKEv2 AUTH载荷中ASN.1摘要的DER编码，导致远程攻击者可通过Bleichenbacher攻击变种伪造AUTH载荷，导致身份冒充；同时，通过编码较短的哈希可触发断言导致拒绝服务。

CVSS 8.1 · High EPSS 0.35% · P26

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
The Libreswan Project libreswan ≤ 5.3 affected
5.3.1 unaffected
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I. Basic Information for CVE-2026-50722

Vulnerability Information
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Vulnerability Title
IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload
Source: CVE Program / CVE List V5
Vulnerability Description
Libreswan, via the function RSA_authenticate_hash_signature_pkcs1_1_5_rsa(), did not correctly verify the DER encoding of the ASN.1 digest when the IKEv2 AUTH payload was encoded using RSASSA-PKCS1-v1_5 (RFC 8017). A remote attacker can use a variation on the Bleichenbacher attack to forge the AUTH payload when small public exponents are used (e.g., e=3), leading to impersonation. Additionally, a remote attacker, by encoding a shorter than expected hash in the AUTH payload, could trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications of the remote IKE peer are not affected.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
密码学签名的验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
libreswan 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Libreswan是Libreswan团队开源的一个IPsec实现。 libreswan 5.3及之前版本存在加密问题漏洞，该漏洞源于函数RSA_authenticate_hash_signature_pkcs1_1_5_rsa()未能正确验证IKEv2 AUTH载荷中ASN.1摘要的DER编码，导致远程攻击者可通过Bleichenbacher攻击变种伪造AUTH载荷，导致身份冒充；同时，通过编码较短的哈希可触发断言导致拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
The Libreswan Project libreswan 0 ~ 5.3 -

II. Public POCs for CVE-2026-50722

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III. Intelligence Information for CVE-2026-50722

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Vendor Advisories for CVE-2026-50722 (3)

Same Patch Batch · The Libreswan Project · 2026-07-02 · 3 CVEs total

CVE-2026-50721 8.1 HIGH IKEv1 Denial of Service via RSA-SHA1 (PKCS#1 Version 1.5 Encrypted) authentication payload
CVE-2026-12413 7.5 HIGH IKEv2 Denial of Service via malformed fragmentation

IV. Related Vulnerabilities

Same product: libreswan
Same vendor: The Libreswan Project
Same weakness: CWE-347

V. Comments for CVE-2026-50722

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