CVE-2026-8956

Analyzed Analyzed - Analysis Complete

Integer Overflow in Firefox Networking JAR Component

Publication date: 2026-05-19

Last updated on: 2026-05-20

Assigner: Mozilla Corporation

Description

Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-05-19

Last Modified

2026-05-20

Generated

2026-06-30

AI Q&A

2026-05-19

EPSS Evaluated

2026-06-28

NVD

CVE-2026-8956

EUVD

EUVD-2026-30904

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 151.0.0 (exc)
mozilla	firefox	to 140.11.0 (exc)
mozilla	thunderbird	to 151.0.0 (exc)
mozilla	thunderbird	to 140.11 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-190	The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer overflow in the Networking: JAR component of Mozilla Firefox. An integer overflow occurs when a calculation exceeds the maximum size that can be stored in an integer variable, potentially leading to unexpected behavior or security issues. This specific vulnerability was addressed and fixed in Firefox version 151 and Firefox ESR 140.11.

Impact Analysis

An integer overflow in a networking component like the JAR handler could potentially be exploited to cause crashes, memory corruption, or other unintended behavior in the browser. This might allow attackers to execute arbitrary code, disrupt service, or compromise the security of the affected system. However, specific impacts are not detailed in the provided information.

Mitigation Strategies

The vulnerability was fixed in Firefox 151 and Firefox ESR 140.11. To mitigate this vulnerability, you should update your Firefox or Firefox ESR browser to at least these versions.

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