CVE-2021-21193
Google Chromium Blink Use-After-Free Vulnerability
Description
CVE-2021-21193 is a high-severity vulnerability affecting Google Chromium Blink. Google Chromium Blink contains a use-after-free vulnerability that allows a remote attacker to potentially exploit heap corruption via a crafted HTML page. This vulnerability could affect multiple web browsers that utilize Chromium, including, but not limited to, Google Chrome, Microsoft Edge, and Opera. CISA has added this vulnerability to its Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. With an EPSS score of 14.80% (94.4th percentile), this vulnerability has a significant probability of exploitation.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| chrome | < 89.0.4389.90 | |
| fedoraproject | fedora | 32 |
| debian | debian linux | 10.0 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://chromereleases.googleblog.com/2021/03/stable-channel-update-for-desktop_12.html(Release Notes)
- https://crbug.com/1186287(Permissions Required)
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/N52OWF4BAP3JNK2QYGU3Q6QUVDZDCIMQ/(Release Notes)
- https://security.gentoo.org/glsa/202104-08(Third Party Advisory)
- https://www.debian.org/security/2021/dsa-4886(Mailing List, Third Party Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21193(US Government Resource)
Weakness Type
CWE-416: Use After Free
Use After Free (UAF) is a vulnerability that occurs when software continues to use a pointer after the memory it references has been freed. Once memory is freed, it may be reallocated for other purposes.
Learn more: CWE-416 — Use After Free
Impact Analysis
CVE-2021-21193 carries a CVSS 3.1 score of 8.8 (HIGH), indicating a high-severity threat. The vulnerability is exploitable over the network with low attack complexity and requires no privileges, though user interaction is required. Successful exploitation can severely compromise data confidentiality, and allow unauthorized modification of data, and cause complete service disruption. Organizations running affected Google Chromium Blink deployments face significant operational risk if this vulnerability remains unpatched.
Exploit Maturity
CVE-2021-21193 is confirmed as actively exploited through its listing in the CISA Known Exploited Vulnerabilities catalog. The EPSS score of 14.80% (94.4th percentile) indicates a significant probability of exploitation. Federal agencies were required to remediate this vulnerability by 2021-11-17 per CISA's binding operational directive.
Remediation
- Apply vendor patches immediately as mandated by CISA KEV: Apply updates per vendor instructions.
- Verify that all instances of Google Chromium Blink have been updated to the latest patched versions.
- If immediate patching is not possible, restrict network access to affected systems using firewall rules and network segmentation to limit exposure.
- Monitor systems for indicators of compromise, including unusual process activity, unexpected network connections, and unauthorized configuration changes.
- Review security logs and conduct threat hunting to determine if the vulnerability was exploited prior to patching.
Technical Details
CVE-2021-21193 affects Google Chromium Blink. Use after free in Blink in Google Chrome prior to 89.0.4389.90 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page. The attack vector is network-based, meaning an attacker can exploit this vulnerability remotely without physical access to the target system. The CVSS score of 8.8 reflects the combination of easy exploitability and severe impact across confidentiality, integrity, and availability.
Frequently Asked Questions
Is CVE-2021-21193 being actively exploited?
Yes. CVE-2021-21193 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation. The EPSS score of 14.80% (94.4th percentile) further indicates a significant exploitation probability.
What products are affected by CVE-2021-21193?
CVE-2021-21193 affects Google Chromium Blink. Organizations using this product should verify their deployments and apply updates immediately.
How do I fix CVE-2021-21193?
Apply updates per vendor instructions. Ensure all affected systems are updated to the latest patched versions. If patching is not immediately possible, implement network-level mitigations to limit exposure.
How severe is CVE-2021-21193?
CVE-2021-21193 has a CVSS 3.1 score of 8.8 (HIGH). This is a high-severity vulnerability that requires immediate attention and remediation.
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