7.5

CVE-2026-47261: bytecodealliance wasmtime Improper Access Control

CVSS: 7.5v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-47261DEBIAN-CVE-2026-47261CGA-6cxm-2wv3-2vh5
Published 15-06-2026Last modified 16-06-2026
Open JSON

Vulnerability summary

CVE-2026-47261 is a high (CVSS 7.5) Improper Access Control vulnerability in bytecodealliance wasmtime. EPSS estimates a 0.50% chance of exploitation in the next 30 days, higher than 41.6% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.50%
0%100%
Low · +0.14 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-8JMW-F257-FJ7M

Timeline

  1. 15-06-2026
    PublishedVulnerability first disclosed.
  2. 16-06-2026
    Last modifiedVulnerability information updated.

Description

Wasmtime is a runtime for WebAssembly. In versions prior to 24.0.9, 36.0.10, and 44.0.2, when a filesystem preopen is given DirPerms::all() and FilePerms::READ without FilePerms::WRITE, this access control mechanism can be bypassed via the wasip2 descriptor.open-at or wasip1 path_open interfaces by opening a file with only the OpenFlags::TRUNCATE oflag. The root cause is that the clause handling OpenFlags::TRUNCATE in crates/wasi/src/filesystem.rs (Dir::open_at, lines 967–969) did not set open_mode |= OpenMode::WRITE;, which is later used for the access control check against FilePerms to determine whether opening the file is permitted; the single-line fix adds that missing assignment, after which the affected calls correctly fail with error-code.not-permitted and ERRNO_PERM respectively. Only wasmtime-wasi embeddings that combine DirPerms::MUTATE with FilePerms::READ are affected by this bug. In particular, the Wasmtime project's wasmtime-cli's use of wasmtime-wasi is not affected, because it always sets FilePerms::all() for all preopens. This issue has been fixed in versions 24.0.9, 36.0.10 and44.0.2.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.50%

Chance of exploitation in the next 30 days

Percentile

42%

Versus all other CVEs

30-day change

+0.14 pp

From 0.36% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.50%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard2 products
  • wizer< 11.0.3-r12
  • zed< 1.5.4-r1
Wolfi2 products
  • wizer< 11.0.3-r12
  • zed< 1.5.4-r1
Bytecodealliance1 product
  • wasmtime< 24.0.9 | ≥ 25.0.0, < 36.0.10 | ≥ 37.0.0, < 44.0.2
Crates.Io1 product
  • wasmtime-wasi≥ 37.0.0, < 44.0.2 | ≥ 25.0.0, < 36.0.10 | < 24.0.9 | ≥ 45.0.0, < 45.0.0
Debian1 product
  • rust-wasmtimeAll versions (No fix recorded) | < 36.0.11+dfsg-1
Ubuntu1 product
  • rust-wasmtimeAll versions (No fix recorded)

6 vendors · 8 products

References

14 links
Show all 14 references