Upstream information
Description
In versions 3.0.0a1 through 3.2.0 of Mistune, there is a ReDoS (Regular Expression Denial of Service) vulnerability in `LINK_TITLE_RE` that allows an attacker who can supply Markdown for parsing to cause denial of service. The regular expression used for parsing link titles contains overlapping alternatives that can trigger catastrophic backtracking. In both the double-quoted and single-quoted branches, a backslash followed by punctuation can be matched either as an escaped punctuation sequence or as two ordinary characters, creating an ambiguous pattern inside a repeated group. If an attacker supplies Markdown containing repeated ! sequences with no closing quote, the regex engine explores an exponential number of backtracking paths. This is reachable through normal Markdown parsing of inline links and block link reference definitions. A small crafted input can therefore cause significant CPU consumption and make applications using Mistune unresponsive.SUSE information
Overall state of this security issue: Pending
This issue is currently rated as having important severity.
| CVSS detail | SUSE |
|---|---|
| Base Score | 7.5 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | None |
| Scope | Unchanged |
| Confidentiality Impact | None |
| Integrity Impact | None |
| Availability Impact | High |
| CVSSv3 Version | 3.1 |
| CVSS detail | CNA (GitHub) | SUSE |
|---|---|---|
| Base Score | 8.7 | 8.7 |
| Vector | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| Attack Vector | Network | Network |
| Attack Complexity | Low | Low |
| Attack Requirements | None | None |
| Privileges Required | None | None |
| User Interaction | None | None |
| Vulnerable System Confidentiality Impact | None | None |
| Vulnerable System Integrity Impact | None | None |
| Vulnerable System Availability Impact | High | High |
| Subsequent System Confidentiality Impact | None | None |
| Subsequent System Integrity Impact | None | None |
| Subsequent System Availability Impact | None | None |
| CVSSv4 Version | 4.0 | 4.0 |
Status of this issue by product and package
Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.
| Product(s) | Source package | State |
|---|---|---|
| Products under general support and receiving all security fixes. | ||
| SUSE Linux Enterprise Desktop 15 SP7 | python-mistune | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Package Hub 15 SP7 | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Python 3 15 SP7 | python-mistune | Not affected |
| SUSE Linux Enterprise Server 15 SP7 | python-mistune | Not affected |
| SUSE Linux Enterprise Server 16.0 | python-mistune | Affected |
| SUSE Linux Enterprise Server 16.1 | python-mistune | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | python-mistune | Not affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | python-mistune | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | python-mistune | Affected |
| Products under Long Term Service Pack support and receiving important and critical security fixes. | ||
| SUSE Linux Enterprise High Performance Computing 15 SP4 | python-mistune | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | python-mistune | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | python-mistune | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Python 3 15 SP4 | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Python 3 15 SP5 | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Python 3 15 SP6 | python-mistune | Not affected |
| SUSE Linux Enterprise Server 15 SP4 | python-mistune | Not affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | python-mistune | Not affected |
| SUSE Linux Enterprise Server 15 SP5 | python-mistune | Not affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | python-mistune | Not affected |
| SUSE Linux Enterprise Server 15 SP6 | python-mistune | Not affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | python-mistune | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | python-mistune | Not affected |
| SUSE Manager Proxy 4.3 | python-mistune | Not affected |
| SUSE Manager Retail Branch Server 4.3 | python-mistune | Not affected |
| SUSE Manager Server 4.3 | python-mistune | Not affected |
| Products past their end of life and not receiving proactive updates anymore. | ||
| SUSE Linux Enterprise Desktop 15 SP4 | python-mistune | Not affected |
| SUSE Linux Enterprise Desktop 15 SP5 | python-mistune | Not affected |
| SUSE Linux Enterprise Desktop 15 SP6 | python-mistune | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | python-mistune | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | python-mistune | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Package Hub 15 SP4 | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Package Hub 15 SP5 | python-mistune | Not affected |
| SUSE Linux Enterprise Module for Package Hub 15 SP6 | python-mistune | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | python-mistune | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | python-mistune | Not affected |
| openSUSE Leap 15.3 | python-mistune | Not affected |
| openSUSE Leap 15.4 | python-mistune | Not affected |
| openSUSE Leap 15.5 | python-mistune | Not affected |
| openSUSE Leap 15.6 | python-mistune | Not affected |
SUSE Timeline for this CVE
CVE page created: Thu May 7 11:10:00 2026CVE page last modified: Fri May 8 15:15:16 2026