Cyber Resilience

CVE-2026-2802

Race Condition in Mozilla Firefox ≤ 148.0

Published
24 February 2026
Modified
13 April 2026
Patch / advisory
CVSS Score v3.1 4.2
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
EPSS Score 0.0014 4th percentile
Risk Priority 33 floored blend · peak EPSS

Summary

CVE-2026-2802 is a medium-severity Race Condition (CWE-362) vulnerability in Mozilla Firefox. Its CVSS base score is 4.2 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-39 (Process Isolation) and SC-4 (Information in Shared System Resources) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-2802 is a race condition vulnerability (CWE-362) in the JavaScript Garbage Collector (GC) component of Mozilla Firefox and Thunderbird. It affects versions prior to Firefox 148 and Thunderbird 148, where the flaw allows concurrent access issues during garbage collection operations in JavaScript execution. The vulnerability has a CVSS v3.1 base score of 4.2 (AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N), rated as Medium severity due to its network accessibility but high attack complexity and requirement for user interaction.

An unauthenticated remote attacker can exploit this vulnerability by crafting malicious web content that triggers the race condition in the JavaScript GC, typically requiring the user to interact with a malicious webpage or link. Successful exploitation could result in limited impacts, such as low-level disclosure of sensitive information or minor modification of data, without affecting availability or escalating privileges.

Mozilla's security advisories (MFSA 2026-13 and MFSA 2026-16) and the associated Bugzilla entry (bug 2011069) confirm the issue was addressed in Firefox 148 and Thunderbird 148. Security practitioners should prioritize updating affected browsers to these patched versions to mitigate the risk, as no workarounds are detailed in the provided references.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Race condition in the JavaScript: GC component. This vulnerability was fixed in Firefox 148 and Thunderbird 148.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2020-6820Same product: Mozilla Firefox
CVE-2024-11708Same product: Mozilla Firefox
CVE-2025-1013Same product: Mozilla Firefox
CVE-2025-3608Same product: Mozilla Firefox
CVE-2024-9936Same product: Mozilla Firefox
CVE-2025-13012Same product: Mozilla Firefox
CVE-2020-6819Same product: Mozilla Firefox
CVE-2024-10468Same product: Mozilla Firefox
CVE-2023-29537Same product: Mozilla Firefox
CVE-2026-74947Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 148.0
mozilla
thunderbird
≤ 148.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V10.4.2
  • V10.4.5
  • V15.1.3
  • V15.4.1

Mitigating Controls (NIST 800-53 r5) AI

Maintaining separate execution domains for each process structurally eliminates unintended concurrent access to the same shared resources.

Preventing unintended information transfer through shared system resources directly addresses the improper concurrent modification that defines a race condition.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require proper synchronization primitives and concurrency testing that prevent race conditions.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Security testing can detect race conditions, but does not prevent them at design or coding time.

prevents

Secure SDLC mandates concurrency controls and synchronization primitives that directly prevent race conditions.

prevents

Application security requirements can specify thread-safety and locking rules, but do not prescribe implementation details.

prevents

Secure architecture principles require proper synchronization and resource isolation, addressing the root cause of CWE-362.

prevents

Secure coding standards explicitly forbid unsafe concurrent access patterns and mandate atomic operations or locks.

References