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VulnerabilityPublished

CVE-2026-115355: Mistune · Path Traversal and XSS in Include directive

Affects bukuSource GCVE Database

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Authoritative record:CVE-2026-115355· High 8.7

Not known to be exploited · CVSS 8.7 High : upgrade to 5.1_6 soon.

Data as of 30 Oct 2026, 07:30 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.08.7
CNA (VulnCheck)CVSS 3.17.5
Patch
Available – fixed in 5.1_6
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade buku to 5.1_6.

Affected software

ProductAffectedFixed in
Homebrewbukupkg:brew/bukuOther threatsAffected
  • >=5.1 <5.1_6
Fixed in
  • 5.1_6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

The Include directive in `src/mistune/directives/include.py` does not validate that the resolved file path stays within the source directory, allowing path traversal via `../` sequences to read arbitrary files. Additionally, error messages and included file contents are rendered without HTML escaping, leading to XSS even when `escape=True`. Affected functions: - Path resolution (lines 27-31) - `block_error()` in html.py (line 140) - `render_html_include()` (line 72) The Include plugin must be explicitly enabled via the plugins parameter.

References

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