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CVE-2026-77205— Denial of Service via sending bogus X.509 certificates

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.

FIPS 模式下的 Libreswan 存在一个安全漏洞：格式错误的接收证书会被拒绝，但未被从 NSS 缓存中删除。因此，具有相同序列号的任何真实证书也会被一并拒绝。此问题可能被滥用，导致合法对等体无法连接。由于对 CVE-2026-14957 的修复存在错误，add_decoded_cert() 函数遗漏了对 CERT_DestroyCertificate() 的调用。发送带有新序列号的虚假证书，可能导致拥有相同序列号的真实证书在系统重启前无法建立连接。

CVSS 3.7 · Low

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-77205

Vulnerability Information
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Vulnerability Title
Denial of Service via sending bogus X.509 certificates
Source: CVE Program / CVE List V5
Vulnerability Description
Libreswan in FIPS mode has a vulnerability where badly formed received certificates are rejected, but not deleted from the NSS cache. As a result, any real certificates with the same serial number are rejected as well. This can be abused to lock out legitimate peers from connecting. The add_decoded_cert() function missed a call to CERT_DestroyCertificate() due to an incorrect fix for CVE-2026-14957. Sending bogus certificates with new serial numbers could prevent the real certificates with those serial numbers from connecting until the service has restarted.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
对已超过有效生命周期的资源丧失索引
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
The Libreswan Project libreswan 5.3 ~ 5.3.2 -

II. Public POCs for CVE-2026-77205

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III. Intelligence Information for CVE-2026-77205

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Vendor Advisories for CVE-2026-77205 (3)

Same Patch Batch · The Libreswan Project · 2026-10-13 · 4 CVEs total

CVE-2026-94453 7.5 HIGH IKEv2 Use-After-Free bug when using IKE-over-TCP
CVE-2026-77206 7.5 HIGH IKEv2 pre-authentication Null Pointer Dereference in EAP code
CVE-2026-77207 7.5 HIGH Null Pointer Dereference in PKCS#7 bundle with no certificates

IV. Related Vulnerabilities

Same product: libreswan
Same vendor: The Libreswan Project
Same weakness: CWE-772

V. Comments for CVE-2026-77205

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