Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosing data on the host's stack to WebAssembly guests. The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests. This bug specifically arose from a mistake where the return value of table.size was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.
CVE-2026-34945
This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 75% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.5
- EG Score
- 6.5(medium)
- EG Risk
- 29(Track)EG Risk 29/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity65% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 25%
- KEV
- Not listed
Published
April 9, 2026
Last Modified
April 20, 2026
References (1)
- security-advisories@githubhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9w2-8782-2946
Affected Packages
(1 across 1 ecosystem)
crates.io(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| wasmtime | — | 43.0.1 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 12× in last 7d / 41× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 102 total refreshes for this CVE.
- 2026-07-26 14:54 UTCEPSS rescore
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Related CVEs(same CWE)
Same CWE
10 shownCWE-681
- CVE-2022-43663NVD 8.1EG 9.8EPSS p96CRITICAL
- CVE-2022-40138EG 9.8CRITICAL
- CVE-2021-36357EG 9.8CRITICAL
- CVE-2021-38187EG 9.8CRITICAL
- CVE-2020-35926EG 9.8CRITICAL
- CVE-2019-19317EG 9.8EPSS p90CRITICAL
- CVE-2019-14842EG 9.8CRITICAL
- CVE-2018-8786EG 9.8EPSS p94CRITICAL
- CVE-2022-36025EG 9.1CRITICAL
- CVE-2021-33742NVD 7.5EG 9.0 KEVEPSS p99CRITICAL
Frequently asked(5)
What is CVE-2026-34945?
When was CVE-2026-34945 disclosed?
Is CVE-2026-34945 actively exploited?
What is the CVSS score of CVE-2026-34945?
How do I remediate CVE-2026-34945?
Dependency Blast Radius
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