Medium [CVE-2026-59925] Denial of Service via crafted Markdown input
This medium-severity Red Hat Linux advisory covers CVE-2026-59925 affecting Migration Toolkit for Applications 8, Red Hat OpenShift AI (RHOAI), Red Hat OpenShift Container Platform 4.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
Mistune is a Python Markdown parser with renderers and plugins.
Prior to 3.3.0, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a character cause quadratic work in src/mistune/inline_parser.py because the parser scans forward for matching close markers from every potential opening run, allowing denial of service in default Mistune parsing. This issue is fixed in version 3.3.0.
An attacker can exploit this vulnerability by providing specially crafted Markdown input containing long sequences of emphasis pairs. This can cause the parser to perform excessive computational work, leading to a denial of service (DoS) condition in the default Mistune parsing.
This can lead to resource exhaustion and service unavailability in applications utilizing Mistune, where user-controlled Markdown input is processed.
Red Hat assigns PR:L in the product-specific CVSS base score because delivering the crafted Markdown document to Mistune requires authenticated access in affected products; platform login and RBAC prevent unauthenticated remote submission in default deployments.
The upstream PR:N score assumes any Internet-facing application parsing untrusted Markdown without authentication. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-1333.
Is CVE-2026-59925 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-59925 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-59925?
Upgrade to a fixed release named by Red Hat:
- 3.3.0
Confirm against the vendor advisory before you patch.
- < 3.3.0
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Get an email when Red Hat publishes the next one.
See Red Hat's last 90 days of advisories first. Then choose one product with live alerts free for life, or a free month of real-time alerts on everything with the severity, the fixed version and the vendor's link (card needed, then US$15/month; we email you before the first charge).
More Red Hat Linux advisories
- CVE-2026-48710May 26, 2026Security restriction bypass via malformed HTTP Host header
- CVE-2026-119977Oct 31, 2026Arbitrary code execution via predictable upgrade staging paths
- CVE-2026-111497Oct 22, 2026Out-of-Bounds Write in Google Brotli Decoder
- CVE-2026-109619Oct 21, 2026fatal error handling retains stale request state leading to use-after-free
- CVE-2026-109618Oct 21, 2026OOM bailout during request parsing leads to memory corruption and RCE
- CVE-2026-97229Oct 13, 2026integer overflow issue in CI/CD regular expression compiler
iPhone and Android apps · New on the App Store
Monitor future Red Hat Linux CVEs from your phone.
Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 34 official vendor sources and 160+ reviewed platform categories.
Discussion(0)
No comments yet. Share field notes, upgrade gotchas, or questions — verify against the vendor advisory before acting on community advice.
Sign in to join the discussion.