How severe is CVE-2026-59927?

CVE-2026-59927 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-59927 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59927?

CVE-2026-59927 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59927?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-59927 published?

CVE-2026-59927 was published on 2026-07-08 and last updated on 2026-07-09.

CVE-2026-59927

CVE-2026-59927 is a medium-severity vulnerability in Mistune Project Mistune with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-674.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-674
Affected product: Mistune Project Mistune
Published: 2026-07-08
Last modified: 2026-07-09

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.

Frequently asked questions

What is CVE-2026-59927?: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the Include directive in src/mistune/directives/include.py detects only direct self-includes and not indirect cycles, allowing two markdown files that include each other to trigger unbounded recursion, raise RecursionError, and crash the rendering request. This issue is fixed in version 3.3.0.
How severe is CVE-2026-59927?: CVE-2026-59927 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-59927 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59927?: CVE-2026-59927 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59927?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-59927 published?: CVE-2026-59927 was published on 2026-07-08 and last updated on 2026-07-09.

References

Affected products (1)

cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*

More vulnerabilities in Mistune Project Mistune

CVE-2026-59928 — High (CVSS 7.5): Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many…
CVE-2026-59925 — High (CVSS 7.5): Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, long sequences of well-formed…
CVE-2026-59922 — High (CVSS 7.5): Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or…
CVE-2022-34749 — High (CVSS 7.5): In mistune through 2.0.2, support of inline markup is implemented by using regular expressions that can involve a high…
CVE-2026-59929 — Medium (CVSS 6.1): Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safe_url filter in…
CVE-2026-59926 — Medium (CVSS 6.1): Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_admonition() in…

All CVEs affecting Mistune Project Mistune →

Other CWE-674 (Uncontrolled Recursion) vulnerabilities

CVE-2026-43185 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix signededness bug in…
CVE-2023-51803 — Critical (CVSS 9.8): LinuxServer.io Heimdall before 2.5.7 does not prevent use of icons that have non-image data such as the "<?php ?>"…
CVE-2021-41752 — Critical (CVSS 9.8): Stack overflow vulnerability in Jerryscript before commit e1ce7dd7271288be8c0c8136eea9107df73a8ce2 on Oct 20, 2021 due…
CVE-2018-1000618 — Critical (CVSS 9.8): EOSIO/eos eos version after commit f1545dd0ae2b77580c2236fdb70ae7138d2c7168 contains a stack overflow vulnerability in…
CVE-2025-10728 — Critical (CVSS 9.4): When the module renders a Svg file that contains a <pattern> element, it might end up rendering it recursively leading…
CVE-2026-32327 — Critical (CVSS 9.1): A bug in APR-util version 1.6.3 (and earlier) allows a stack recursion attack against any library consumer which parses…

Browse all CWE-674 (Uncontrolled Recursion) vulnerabilities →