CVE-2026-100771 (CVSS 8.1)

Description

Undefined behavior in the DOM: Streams component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0031

Probability of exploitation

0.24%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-758 CWE-758

References

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=2068336 https://www.mozilla.org/security/advisories/mfsa2026-100/ https://www.mozilla.org/security/advisories/mfsa2026-101/ https://www.mozilla.org/security/advisories/mfsa2026-102/ https://www.mozilla.org/security/advisories/mfsa2026-103/ https://www.mozilla.org/security/advisories/mfsa2026-97/ https://www.mozilla.org/security/advisories/mfsa2026-98/ https://www.mozilla.org/security/advisories/mfsa2026-99/

Frequently Asked Questions

What is CVE-2026-100771? +

Undefined behavior in the DOM: Streams component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-100771? +

CVE-2026-100771 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0031, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-100771? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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