CVE-2021-38496
HIGHCVSS 8.8/10EPSS 1.59%
Last modified
CVE-2021-38496 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.. EPSS estimates a 1.59% chance of exploitation in the next 30 days.
Description
During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | < 93.0 |
| Mozilla | Firefox | >= 91.0, < 91.2 |
| Mozilla | Firefox Esr | < 78.15 |
| Mozilla | Thunderbird | < 78.15 |
| Mozilla | Thunderbird | >= 91.0, < 91.2 |
| Debian | Debian Linux | 9.0 |
| Debian | Debian Linux | 10.0 |
| Debian | Debian Linux | 11.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1725335Issue Tracking, Permissions Required, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing List, Third Party Advisory
- https://www.debian.org/security/2022/dsa-5034Issue Tracking, Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-43/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-44/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-45/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-47/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1725335Issue Tracking, Permissions Required, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing List, Third Party Advisory
- https://www.debian.org/security/2022/dsa-5034Issue Tracking, Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-43/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-44/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-45/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-47/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-38496?
During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.
How severe is CVE-2021-38496?
CVE-2021-38496 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 1.59% probability of exploitation in the next 30 days.
How do I fix CVE-2021-38496?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-38496?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST