VulnerabilityRUSTSEC-2021-0157 · ammonia
RUSTSEC-2021-0157: Incorrect escaping for `url("")` functions in CSS style attributes
Short answerA security vulnerability in the ammonia crate: Incorrect escaping for `url("")` functions in CSS style attributes. No severity score was published. Fixed in 4.1.7, 4.2.3: update to a fixed version.
| Crate | ammonia |
|---|---|
| Type | Vulnerability (format-injection) |
| Affected versions | Before 4.1.7; from 4.2.0 before 4.2.3. |
| Fixed in | 4.1.7, 4.2.3 |
| Severity | not scored |
| Published | 2021-10-10 |
| Last changed | 2026-10-12 |
| Also known as | GHSA-69v2-w9vg-4g83 |
What to do
- See which version you have:
cargo tree -i ammonia(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p ammonia. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for exampleammonia = "4.2.3") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
In some cases, quotation marks in CSS url() functions are not escaped. This allows CSS injection. This feature is not enabled by default, so an application is vulnerable if, and only if, the style attribute is allowed and filter_style_properties is used.
As an example, this snippet:
<div style='background:url("cid:\");EVIL_CSS_HERE;background:url(\"cid:")'>Would erroneously "sanitize" to:
<div style='background:url("cid:");EVIL_CSS_HERE;background:url("cid:")'>---
This vulnerability was reported by Uttej Badwane
References
- Package: crates.io/crates/ammonia
- Advisory: rustsec.org/advisories/RUSTSEC-2021-0157.html
- Web: github.com/rust-ammonia/ammonia/pull/259
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
Other advisories for ammonia
- Vulnerability HighRUSTSEC-2019-0001 · 2019-04-27Uncontrolled recursion leads to abort in HTML serialization
- VulnerabilityRUSTSEC-2021-0074 · 2021-07-08Incorrect handling of embedded SVG and MathML leads to mutation XSS
- VulnerabilityRUSTSEC-2021-0158 · 2021-10-10XSS in ammonia via SVG `animateMotion`, `animateTransform`, and/or `animateColor` tags
- VulnerabilityRUSTSEC-2022-0003 · 2022-01-19Space bug in `clean_text`
- VulnerabilityRUSTSEC-2025-0071 · 2025-09-21Incorrect handling of embedded SVG and MathML leads to mutation XSS after removal
- VulnerabilityRUSTSEC-2026-0193 · 2026-06-30mXSS in ammonia via MathML `annotation-xml` encoding strip
- VulnerabilityRUSTSEC-2026-0213 · 2026-07-21XSS in ammonia via SVG `animate` and `set` animation tags
- VulnerabilityRUSTSEC-2026-0373 · 2026-10-16Missing case-insensitive matching for CSS url function
Up next
Same crateammonia: security historyEvery advisory for this crate, and whether it is safe to use today.Read it next →Did this answer your question?