CVE-2021-27671
Cross site scripting in comrak
An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
- Record
CVE-2021-27671- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:N/I:P/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
- Record
CVE-2021-27671- Updated
- 2026-11-02
EUVDEUVD-2021-1936 No score
An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
- Record
EUVD-2021-1936- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-xmr7-v725-2jjr
Cross site scripting in comrak
An issue was discovered in the comrak crate before 0.9.1 for Rust. Cross site scripting (XSS) can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
- Record
GHSA-xmr7-v725-2jjr- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
- Record
CVE-2021-27671- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-xmr7-v725-2jjr
Cross site scripting in comrak
An issue was discovered in the comrak crate before 0.9.1 for Rust. Cross site scripting (XSS) can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
- Record
GHSA-xmr7-v725-2jjr- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSVRUSTSEC-2021-0026
XSS in `comrak`
The comrak we were matching unsafe URL prefixes, such as data: or javascript: , in a case-sensitive manner. This meant prefixes like Data: were untouched.
- Record
RUSTSEC-2021-0026- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-27671 is a medium vulnerability (CVSS 6.1) in Comrak Project Comrak, published February 21, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.69%, the 52nd percentile. Fixed in comrak 0.9.1.