Remote code execution via reentrant popover teardown
Published Feb 24, 2026 · Updated Feb 24, 2026
Use-after-free in Mozilla Firefox and Thunderbird before 148 allows remote attackers to execute code through crafted web content. Document::HidePopover retains a raw PopoverData pointer across synchronous beforetoggle dispatch, then calls SetInvoker after a handler frees and replaces that object. Exploitation requires attacker-controlled JavaScript and user interaction; Thunderbird blocks scripting while reading mail, limiting exposure to browser-like contexts.
Summary
What happened
Use-after-free in Mozilla Firefox and Thunderbird before 148 allows remote attackers to execute code through crafted web content. Document::HidePopover retains a raw PopoverData pointer across synchronous beforetoggle dispatch, then calls SetInvoker after a handler frees and replaces that object. Exploitation requires attacker-controlled JavaScript and user interaction; Thunderbird blocks scripting while reading mail, limiting exposure to browser-like contexts.
The record
- CVE
- CVE-2026-2798
- Published
- Feb 24, 2026
- Updated
- Feb 24, 2026
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-416, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 24, 2026CVE publishedPublication date reported by the CVE source.
- Feb 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <148
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- popover_hide_uaf.htmlproof of concept · demonstrated
- popover_hide_uaf_spray.htmlproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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