CVE-2026-39972

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Source
https://cve.org/CVERecord?id=CVE-2026-39972
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39972.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-39972
Aliases
Related
Published
2026-04-09T16:42:22.903Z
Modified
2026-07-08T08:13:07.285356664Z
Severity
  • 7.1 (High) CVSS_V4 - 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 CVSS Calculator
Summary
Mercure has a Topic Selector Cache Key Collision
Details

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.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39972.json",
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-1289"
    ]
}
References

Affected packages

Git / github.com/dunglas/mercure

Affected ranges

Type
GIT
Repo
https://github.com/dunglas/mercure
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
4964a69be904fd61e35b5f1e691271663b6fdd64
Database specific 
{
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ],
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "0.22.0"
        }
    ]
}

Affected versions

caddy/v0.*
caddy/v0.11.3
caddy/v0.12.0
caddy/v0.12.1
caddy/v0.12.2
caddy/v0.13.0
caddy/v0.14.0
caddy/v0.14.0-beta.1
caddy/v0.14.0-beta.2
caddy/v0.14.1
caddy/v0.14.10
caddy/v0.14.2
caddy/v0.14.3
caddy/v0.14.4
caddy/v0.14.5
caddy/v0.14.6
caddy/v0.14.8
caddy/v0.14.9
caddy/v0.15.0
caddy/v0.15.1
caddy/v0.15.10
caddy/v0.15.11
caddy/v0.15.2
caddy/v0.15.3
caddy/v0.15.4
caddy/v0.15.5
caddy/v0.15.6
caddy/v0.15.7
caddy/v0.15.8
caddy/v0.15.9
caddy/v0.16.0
caddy/v0.16.1
caddy/v0.16.2
caddy/v0.16.3
caddy/v0.17.0
caddy/v0.17.1
caddy/v0.18.0
caddy/v0.18.1
caddy/v0.18.2
caddy/v0.18.3
caddy/v0.18.4
caddy/v0.19.0
caddy/v0.19.1
caddy/v0.19.2
caddy/v0.19.3
caddy/v0.20.0
caddy/v0.20.1
caddy/v0.20.2
caddy/v0.21.1
caddy/v0.21.10
caddy/v0.21.11
caddy/v0.21.2
caddy/v0.21.3
caddy/v0.21.4
caddy/v0.21.5
caddy/v0.21.6
caddy/v0.21.7
caddy/v0.21.8
caddy/v0.21.9
helm-chart-0.*
helm-chart-0.11.3
helm-chart-0.12.0
helm-chart-0.12.1
helm-chart-0.12.2
helm-chart-0.13.0
helm-chart-0.14.0
helm-chart-0.14.0-beta.1
helm-chart-0.14.0-beta.2
helm-chart-0.14.1
helm-chart-0.14.10
helm-chart-0.14.2
helm-chart-0.14.3
helm-chart-0.14.4
helm-chart-0.14.5
helm-chart-0.14.6
helm-chart-0.14.8
helm-chart-0.14.9
helm-chart-0.15.0
helm-chart-0.15.1
helm-chart-0.15.10
helm-chart-0.15.11
helm-chart-0.15.2
helm-chart-0.15.3
helm-chart-0.15.4
helm-chart-0.15.5
helm-chart-0.15.6
helm-chart-0.15.7
helm-chart-0.15.8
helm-chart-0.15.9
helm-chart-0.16.0
helm-chart-0.16.1
helm-chart-0.16.2
helm-chart-0.16.3
helm-chart-0.17.0
helm-chart-0.17.1
helm-chart-0.18.0
helm-chart-0.18.1
helm-chart-0.18.2
helm-chart-0.18.3
helm-chart-0.18.4
helm-chart-0.19.0
helm-chart-0.19.1
helm-chart-0.19.2
helm-chart-0.19.3
helm-chart-0.20.0
helm-chart-0.20.1
helm-chart-0.20.2
helm-chart-0.21.1
helm-chart-0.21.10
helm-chart-0.21.11
helm-chart-0.21.2
helm-chart-0.21.3
helm-chart-0.21.4
helm-chart-0.21.5
helm-chart-0.21.6
helm-chart-0.21.7
helm-chart-0.21.8
helm-chart-0.21.9
v0.*
v0.1.0
v0.10.0
v0.10.1
v0.10.2
v0.10.3
v0.10.4
v0.11.0
v0.11.0-beta.1
v0.11.0-beta.2
v0.11.0-rc.1
v0.11.0-rc.2
v0.11.0-rc.3
v0.11.1
v0.11.2
v0.11.3
v0.12.0
v0.12.1
v0.12.2
v0.13.0
v0.14.0
v0.14.0-beta.1
v0.14.0-beta.2
v0.14.1
v0.14.10
v0.14.2
v0.14.3
v0.14.4
v0.14.5
v0.14.6
v0.14.8
v0.14.9
v0.15.0
v0.15.1
v0.15.10
v0.15.11
v0.15.2
v0.15.3
v0.15.4
v0.15.5
v0.15.6
v0.15.7
v0.15.8
v0.15.9
v0.16.0
v0.16.1
v0.16.2
v0.16.3
v0.17.0
v0.17.1
v0.18.0
v0.18.1
v0.18.2
v0.18.3
v0.18.4
v0.19.0
v0.19.1
v0.19.2
v0.19.3
v0.2.0
v0.2.1
v0.2.2
v0.2.3
v0.2.4
v0.2.5
v0.20.0
v0.20.1
v0.20.2
v0.21.0
v0.21.1
v0.21.10
v0.21.11
v0.21.2
v0.21.3
v0.21.4
v0.21.5
v0.21.6
v0.21.7
v0.21.8
v0.21.9
v0.3.0
v0.3.1
v0.3.2
v0.3.3
v0.4.0
v0.4.1
v0.4.2
v0.5.0
v0.5.1
v0.6.0
v0.6.1
v0.6.2
v0.7.0
v0.7.1
v0.7.2
v0.8.0
v0.8.1
v0.9.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39972.json"