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CVE-2025-1933JIT corruption of WASM i32 return values on 64-bit CPUs
- 7.6HighCVSS base score
- 0.32%Exploitation in 30 daysEPSS · top 75% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
On 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory. This can potentially cause them to be treated as a different type. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.
Timeline
ID reserved
By mozilla
Published
- 15 months later
· 15 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | High7.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H |
| NVDNVD · Modified | 3.1 | High7.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H |
- EPSS (exploitation in 30 days)
- 0.32% · top 75% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.6.
Affected products
- unaffected 115.21 – ≤ 115.*
- unaffected 128.8 – ≤ 128.*
- unaffected 136 – ≤ *
- unaffected 128.8 – ≤ 128.*
- unaffected 136 – ≤ *
References
References7
- https://bugzilla.mozilla.org/show_bug.cgi?id=1946004 (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2025-14/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2025-15/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2025-16/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2025-17/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2025-18/ (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/03/msg00006.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-7438 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-1933)Record last updated .