How severe is CVE-2026-100759?

CVE-2026-100759 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-100759 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-100759?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-100759 published?

CVE-2026-100759 was published on 2026-09-29 and last updated on 2026-10-01.

CVE-2026-100759

CVE-2026-100759 is a high-severity vulnerability with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-457.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-457
Published: 2026-09-29
Last modified: 2026-10-01

Description

Uninitialized memory in the Storage: Quota Manager 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.

Frequently asked questions

What is CVE-2026-100759?: Uninitialized memory in the Storage: Quota Manager 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.
How severe is CVE-2026-100759?: CVE-2026-100759 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-100759 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-100759?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-100759 published?: CVE-2026-100759 was published on 2026-09-29 and last updated on 2026-10-01.

References

Other CWE-457 vulnerabilities

CVE-2026-6748 — Critical (CVSS 9.8): Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 150, Firefox ESR…
CVE-2025-54874 — Critical (CVSS 9.8): OpenJPEG is an open-source JPEG 2000 codec. In OpenJPEG from 2.5.1 through 2.5.3, a call to opj_jp2_read_header may…
CVE-2025-53644 — Critical (CVSS 9.8): OpenCV is an Open Source Computer Vision Library. Versions 4.10.0 and 4.11.0 have an uninitialized pointer variable on…
CVE-2026-78935 — Critical (CVSS 9.6): Use of uninitialized variable in Mobile in Google Chrome on on iOS prior to 152.0.7977.65 allowed a remote attacker to…
CVE-2026-14405 — Critical (CVSS 9.6): Uninitialized Use in V8 in Google Chrome prior to 150.0.7871.46 allowed a remote attacker to execute arbitrary code…
CVE-2026-84639 — Critical (CVSS 9.1): Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability…

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