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CVE-2026-27135— nghttp2 Denial of service: Assertion failure due to the missing state validation

Quick assessment

Affected
nghttp2 nghttp2
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

nghttp2是nghttp2开源的一个 C 库。 nghttp2 1.68.1之前版本存在安全漏洞，该漏洞源于缺少内部状态验证，可能导致断言失败。

CVSS 7.5 · High EPSS 0.78% · P53

Affected Version Matrix 1

VendorProduct Version RangeStatus
nghttp2 nghttp2 < 1.68.1 affected
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I. Basic Information for CVE-2026-27135

Vulnerability Information
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Vulnerability Title
nghttp2 Denial of service: Assertion failure due to the missing state validation
Source: CVE Program / CVE List V5
Vulnerability Description
nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. Prior to version 1.68.1, the nghttp2 library stops reading the incoming data when user facing public API `nghttp2_session_terminate_session` or `nghttp2_session_terminate_session2` is called by the application. They might be called internally by the library when it detects the situation that is subject to connection error. Due to the missing internal state validation, the library keeps reading the rest of the data after one of those APIs is called. Then receiving a malformed frame that causes FRAME_SIZE_ERROR causes assertion failure. nghttp2 v1.68.1 adds missing state validation to avoid assertion failure. No known workarounds are available.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
可达断言
Source: CVE Program / CVE List V5
Vulnerability Title
nghttp2 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
nghttp2是nghttp2开源的一个 C 库。 nghttp2 1.68.1之前版本存在安全漏洞，该漏洞源于缺少内部状态验证，可能导致断言失败。
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
nghttp2 nghttp2 < 1.68.1 -

II. Public POCs for CVE-2026-27135

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 9060 chars
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III. Intelligence Information for CVE-2026-27135

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Patches & Fixes for CVE-2026-27135 (1)

Vendor Advisories for CVE-2026-27135 (1)

IV. Related Vulnerabilities

Same product: nghttp2
Same vendor: nghttp2
Same weakness: CWE-617

V. Comments for CVE-2026-27135

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