Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-39972— Mercure has a Topic Selector Cache Key Collision

Quick assessment

Affected
dunglas mercure
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.

mercure是Kévin Dunglas个人开发者的一个实时数据推送协议及服务器实现。 Mercure 0.22.0之前版本存在安全漏洞，该漏洞源于TopicSelectorStore中的缓存键冲突，可能导致攻击者毒化匹配结果缓存，绕过私有更新的授权检查。

AI Predicted 7.5 Difficulty: Easy EPSS 0.42% · P34

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-39972

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Mercure has a Topic Selector Cache Key Collision
Source: CVE Program / CVE List V5
Vulnerability Description
Mercure is a protocol for pushing data updates to web browsers and other HTTP clients in a battery-efficient way. Prior to 0.22.0, a cache key collision vulnerability in TopicSelectorStore allows an attacker to poison the match result cache, potentially causing private updates to be delivered to unauthorized subscribers or blocking delivery to authorized ones. The cache key was constructed by concatenating the topic selector and topic with an underscore separator. Because both topic selectors and topics can contain underscores, two distinct pairs can produce the same key. An attacker who can subscribe to the hub or publish updates with crafted topic names can exploit this to bypass authorization checks on private updates. This vulnerability is fixed in 0.22.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1289
Source: CVE Program / CVE List V5
Vulnerability Title
mercure 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
mercure是Kévin Dunglas个人开发者的一个实时数据推送协议及服务器实现。 Mercure 0.22.0之前版本存在安全漏洞，该漏洞源于TopicSelectorStore中的缓存键冲突，可能导致攻击者毒化匹配结果缓存，绕过私有更新的授权检查。
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
dunglas mercure < 0.22.0 -

II. Public POCs for CVE-2026-39972

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-39972

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-39972 (1)

Vendor Advisories for CVE-2026-39972 (1)

IV. Related Vulnerabilities

Same weakness: CWE-1289

V. Comments for CVE-2026-39972

No comments yet

Leave a comment