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Vulnerabilities

Security incident · CVE-2026-73054

SiYuan: A parser differential between the WebSocket keepalive exemption and the session quarantine allows unauthenticated access to the broadcast event stream

Published Aug 15, 2026 · catalog updated Oct 23, 2026 · SiYuan: A parser differential

Check if you run it

No confirmed exploitation is on record for CVE-2026-73054. EPSS is 0.54%. Act only if a listed version of SiYuan: A parser differential is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (SiYuan: A parser differential).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.54%
Remediation
Version ranges on file
Affected products
Go github.com/siyuan-note/siyuan/kernel · go github.com/siyuan-note/siyuan/kernel · golang github.com · vendor siyuan-note siyuan

### Summary Two checks on the same WebSocket request URI parse it differently. The authentication exemption for keepalive sessions matches raw substrings, while the quarantine introduced to contain those sessions reads a parsed query parameter. Because Go's returns only the first value for a repeated key, a single URI can satisfy the exemption and still resolve to a non-auth session identity. The result is that an unauthenticated remote caller connects to the kernel WebSocket with a valid access auth code configured, is placed in the general broadcast pool rather than the quarantined pool, and receives the live event stream. ### Details **The exemption matches substrings.** on the development branch, on master: Neither operand is parsed. Any URI containing both literals is exempted, regardless of what the query actually resolves to. **The quarantine parses.** Commit added the containment for exempted sessions at : returns the first value for a repeated key. **The differential.** For the URI: - It contains and , so is true. No cookie, no JWT and no access auth code are required. - returns , so is false. files the session in , the broadcast pool, rather than in . - returns , so the session matches . - Without a valid the publish flag is never set, so does not exclude it either. Every guard that should have caught the session keys off a different parse than the one that admitted it. **No origin validation.** does not appear on the path, so the cross-origin vector described in the parent advisory also remains available. **Distinction from the existing broadcast-pool advisory.** GHSA-mw8r-mw84-88v2 concerns the publish port, where an anonymous session is expected to connect and the defect is that broadcast content is not gated for it afterwards. This report concerns the kernel port with an access auth code configured, where the session should never be admitted in the first place. The leaked data overlaps because both end in the same broadcast pool, but the mechanisms and

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Go github.com/siyuan-note/siyuan/kernel0 → 0.0.0-20260731131820-67bc300b6ea6
  • go github.com/siyuan-note/siyuan/kernel< 0.0.0-20260731131820-67bc300b6ea6
  • golang github.comversion unspecified
  • vendor siyuan-note siyuanversion unspecified

How to fix CVE-2026-73054

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-73054. EPSS is 0.54%. Act only if a listed version of SiYuan: A parser differential is installed.

Which versions are affected?

Compare what you have installed with 0 → 0.0.0-20260731131820-67bc300b6ea6, < 0.0.0-20260731131820-67bc300b6ea6. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-287: Improper Authentication. EPSS 0.54%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · GitHub Advisory Database

    Detected

    ### Summary Two checks on the same WebSocket request URI parse it differently. The authentication exemption for keepalive sessions matches raw substrings, while the quarantine introduced to contain those sessions reads a parsed query parameter. Because Go's returns only the first value for a repeated key, a single URI can satisfy the exemption and still resolve to a non-auth session identity. The

  2. Oct 23, 2026 · GitHub Advisory Database

    Fix available

    github.com/siyuan-note/siyuan/kernel fixed in 0.0.0-20260731131820-67bc300b6ea6

  3. Oct 23, 2026 · GitHub Advisory Database

    Fix available

    github.com/siyuan-note/siyuan/kernel fixed in 0.0.0-20260731131820-67bc300b6ea6

  4. Oct 23, 2026 · GitHub Advisory Database

    Updated

    ### Summary Two checks on the same WebSocket request URI parse it differently. The authentication exemption for keepalive sessions matches raw substrings, while the quarantine introduced to contain those sessions reads a parsed query parameter. Because Go's returns only the first value for a repeated key, a single URI can satisfy the exemption and still resolve to a non-auth session identity. The

Sources

  • CVE.orgVulnerability recordCVE-2026-73054

    SiYuan versions before v3.7.4 contain an authentication bypass vulnerability in the WebSocket endpoint caused by differential parsing of query parameters between authentication exemption and session quarantine checks. Unauthenticated attackers can craft a malicious WebSocket URI

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-73054

    30-day exploitation probability 0.54%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-c8w8-3pqp-wr83

    SiYuan: A parser differential between the WebSocket keepalive exemption and the session quarantine allows unauthenticated access to the broadcast event stream

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-73054

    Two checks on the same WebSocket request URI parse it differently. The authentication exemption for keepalive sessions matches raw substrings, while the quarantine introduced to contain those sessions reads a parsed query parameter. Because Go's url.Values.Get returns only the first value for a repeated key, a single URI can satisfy the exemption and still resolve to a non-auth session identity. T

    advisories.gitlab.com
  • Go Vulnerability DatabasePackage advisoryGHSA-c8w8-3pqp-wr83

    SiYuan: A parser differential between the WebSocket keepalive exemption and the session quarantine allows unauthenticated access to the broadcast event stream

    osv.dev
  • OpenSSF OSV / OSV ScannerPackage advisoryGHSA-c8w8-3pqp-wr83

    SiYuan: A parser differential between the WebSocket keepalive exemption and the session quarantine allows unauthenticated access to the broadcast event stream

    osv.dev

References

Freshness

Last verified in this catalog Oct 24, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.