Conversion hang via overlapping RGB regex groups
Published Jan 6, 2021 · Updated Aug 3, 2024
Regular expression denial of service in Kozea CairoSVG before 2.5.1 allows attackers to hang SVG conversion via a malicious SVG. The RGB and RGBA patterns in cairosvg/colors.py combine whitespace quantifiers with a lazy capture group, causing cubic backtracking when an rgb() value contains a long run of spaces without a closing parenthesis. A victim or consuming application must process the attacker-controlled file; exploitation pins the conversion process at full CPU for a prolonged period.
Summary
What happened
Regular expression denial of service in Kozea CairoSVG before 2.5.1 allows attackers to hang SVG conversion via a malicious SVG. The RGB and RGBA patterns in cairosvg/colors.py combine whitespace quantifiers with a lazy capture group, causing cubic backtracking when an rgb() value contains a long run of spaces without a closing parenthesis. A victim or consuming application must process the attacker-controlled file; exploitation pins the conversion process at full CPU for a prolonged period.
The record
- CVE
- CVE-2021-21236
- Published
- Jan 6, 2021
- Updated
- Aug 3, 2024
- Vendor
- Kozea
- Product
- CairoSVG
- Classifications
- CWE-400, T1499.004
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Jan 6, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.5.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Malformed rgb() SVG reproductionproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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