CVE-2026-115351
Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Option
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Option
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
- Record
CVE-2026-115351- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N - CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N - Weakness
- CWE-94
- Updated
- 2026-11-02
EUVDEUVD-2026-108420
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
- Record
EUVD-2026-108420- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-2jmw-jfgq-rw98
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers...
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
- Record
GHSA-2jmw-jfgq-rw98- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/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 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N - Weakness
- CWE-94
- Updated
- 2026-11-02
NVD
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
- Record
CVE-2026-115351- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/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 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N - Weakness
- CWE-94
- Updated
- 2026-11-02
OSV
Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Option
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
- Record
CVE-2026-115351- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-94
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-115351
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
- Record
DEBIAN-CVE-2026-115351- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/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 - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-115351
Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
- Record
UBUNTU-CVE-2026-115351- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N - CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
mistuneDebian:12 |
All versions, plus listed versions 2.0.4-12.0.4-23.0.2-13.0.2-23.1.3-13.1.4-13.3.4-13.4.0-1 |
None known |
mistuneDebian:13 |
All versions, plus listed versions 3.1.3-13.1.4-13.3.4-13.4.0-1 |
None known |
mistuneDebian:14 |
All versions, plus listed versions 3.1.3-13.1.4-13.3.4-13.4.0-1 |
None known |
mistuneUbuntu:16.04:LTS |
All versions, plus listed versions 0.6-20.7.1-1 |
None known |
mistuneUbuntu:18.04:LTS |
All versions, plus listed versions 0.7.4-10.8-10.8.1-10.8.3-2 |
None known |
mistuneUbuntu:20.04:LTS |
All versions, plus listed versions 0.8.4-10.8.4-2 |
None known |
mistuneUbuntu:22.04:LTS |
All versions, plus listed versions 0.8.4-40.8.4-52.0.0-1+really0.8.4-1 |
None known |
mistuneUbuntu:24.04:LTS |
All versions, plus listed versions 2.0.4-23.0.2-1 |
None known |
mistuneUbuntu:26.10 |
All versions, plus listed versions 3.1.4-1 |
None known |
mistuneUbuntu:26.04:LTS |
All versions, plus listed versions 3.1.3-13.1.4-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-115351 is a medium vulnerability (CVSS 5.3) in Lepture Mistune, published October 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. No source names a fixed version.
References
github.com/lepture/mistune/security/advisories/GHSA-xmwc-wjpr-q378
vulncheck.com/advisories/mistune-3.2.1-before-3.3.0-css-injection-via-figure-directive-figwidth-option
nvd.nist.gov/vuln/detail/CVE-2026-115351
security-tracker.debian.org/tracker/CVE-2026-115351
ubuntu.com/security/CVE-2026-115351
cve.org/CVERecord?id=CVE-2026-115351