WeasyPrint: CSS Injection via Presentational Hints
WeasyPrint helps web developers to create PDF documents. Prior to 69.0, WeasyPrint embeds unescaped HTML presentational-hint attribute values into CSS in weasyprint/css/__init__.py when presentational_hints=True. The background attribute is inserted into a background-image:url() declaration and parsed by tinycss2.parse_blocks_contents(), allowing untrusted HTML to inject additional CSS declarations. Applications that render untrusted HTML with presentational hints enabled can be affected by CSS injection and server-side requests through injected url() values. This issue is fixed in version 69.0.
- Published
- Aug 18, 2026
- Updated
- Sep 18, 2026
- EPSS
- 0.4% · 29th percentile
- CWE
- CWE-74
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Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 6.5
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
Kozea WeasyPrint
- < 69.0affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | weasyprint | all versions | — |
| Debian:14 | weasyprint | before 69.0-1 | 69.0-1 |
| openSUSE:Leap 16.0 | python-weasyprint | before 65.1-bp160.3.1 | 65.1-bp160.3.1 |
| openSUSE:Tumbleweed | python-weasyprint | before 69.0-1.1 | 69.0-1.1 |
| PyPI | weasyprint | up to and including 68.1 | — |
Same product
kozea: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-68616WeasyPrint Vulnerable to Server-Side Request Forgery (SSRF) Protection Bypass via HTTP Redirect30Monitor
- CVE-2024-28184WeasyPrint allows the attachment of arbitrary files and URLs to a PDF29Monitor
- CVE-2026-55073WeasyPrint restrictive URL fetcher bypass allows local file read and SSRF24Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Kozea WeasyPrint | 69.0 · description | Vendor (CNA) |
| debian:weasyprint | 69.0-1 · Debian:14 | Package registry (OSV) |
| opensuse:python-weasyprint | 69.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- low · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- Low
- Availability impact
- None
Weakness class (CWE)
CWE-74 · Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- HTTP Request SplittingCAPEC-105likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
- Format String InjectionCAPEC-135likelihood: High · High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/Kozea/WeasyPrint/commit/e158264e33fa399b29f415d30719c1d85a55df1d
- github.com/Kozea/WeasyPrint/pull/2773
- github.com/Kozea/WeasyPrint/releases/tag/v69.0
- github.com/Kozea/WeasyPrint/security/advisories/GHSA-jhhc-3hcp-qhm5
Vendor advisories and official records. Exploit/PoC links are deliberately left out.