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CVE-2024-34346

Deno contains a permission escalation via open of privileged files with missing `--deny` flag

8.5 HighFix available

Deno is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults. The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all. Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox. Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations. Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
Low
Privileges needed
High
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.37%Up 0.3 points since May 8, 2024
90%50%10%1%

What each source reports

CVE List Score used 8.5

Deno contains a permission escalation via open of privileged files with missing `--deny` flag

Deno is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults. The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all. Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox. Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations. Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Record
CVE-2024-34346
CVSS 3.1
8.5 HighCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
EUVDEUVD-2024-1344 8.5

Deno is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults. The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all. Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox. Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations. Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Record
EUVD-2024-1344
CVSS 3.1
8.5 HighCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-23rx-c3g5-hv9w 8.4

Deno permission escalation vulnerability via open of privileged files with missing `--deny` flag

The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all.

Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox.

Impact

Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations.

Patches

Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Workarounds

The security sandbox in previous versions of Deno allows for denial of access to these files, but it requires an explicit addition of deny flags: --deny-read=/dev --deny-read=/sys --deny-read=/proc --deny-read=/etc --deny-write=/dev --deny-write=/sys --deny-write=/proc --deny-write=/etc. Note that symlinks in allowed locations may defeat this protection in earlier versions of Deno.

Reporters

This vulnerability was reported by a number of analysts. Thanks to [email protected], [email protected], @leesh3288, and @cristianstaicu for their reports and analysis.

Record
GHSA-23rx-c3g5-hv9w
CVSS 3.1
8.4 HighCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
NVD 8.4

Deno is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults. The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all. Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox. Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations. Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Record
CVE-2024-34346
CVSS 3.1
8.4 HighCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
CVSS 3.1
9.0 CriticalCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
OSV 8.4

Deno contains a permission escalation via open of privileged files with missing `--deny` flag

Deno is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults. The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all. Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox. Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations. Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Record
CVE-2024-34346
CVSS 3.1
8.4 HighCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
OSVGHSA-23rx-c3g5-hv9w 8.4

Deno permission escalation vulnerability via open of privileged files with missing `--deny` flag

The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all.

Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox.

Impact

Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations.

Patches

Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Workarounds

The security sandbox in previous versions of Deno allows for denial of access to these files, but it requires an explicit addition of deny flags: --deny-read=/dev --deny-read=/sys --deny-read=/proc --deny-read=/etc --deny-write=/dev --deny-write=/sys --deny-write=/proc --deny-write=/etc. Note that symlinks in allowed locations may defeat this protection in earlier versions of Deno.

Reporters

This vulnerability was reported by a number of analysts. Thanks to [email protected], [email protected], @leesh3288, and @cristianstaicu for their reports and analysis.

Record
GHSA-23rx-c3g5-hv9w
CVSS 3.1
8.4 HighCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
OSVJLSEC-2026-107 9.0

Deno permission escalation vulnerability via open of privileged files with missing `--deny` flag

The Deno sandbox may be unexpectedly weakened by allowing file read/write access to privileged files in various locations on Unix and Windows platforms. For example, reading /proc/self/environ may provide access equivalent to --allow-env, and writing /proc/self/mem may provide access equivalent to --allow-all.

Users who grant read and write access to the entire filesystem may not realize that these access to these files may have additional, unintended consequences. The documentation did not reflect that this practice should be undertaken to increase the strength of the security sandbox.

Impact

Users who run code with --allow-read or --allow-write may unexpectedly end up granting additional permissions via file-system operations.

Patches

Deno 1.43 and above require explicit --allow-all access to read or write /etc, /dev on unix platform (as well as /proc and /sys on linux platforms), and any path starting with \\ on Windows.

Workarounds

The security sandbox in previous versions of Deno allows for denial of access to these files, but it requires an explicit addition of deny flags: --deny-read=/dev --deny-read=/sys --deny-read=/proc --deny-read=/etc --deny-write=/dev --deny-write=/sys --deny-write=/proc --deny-write=/etc. Note that symlinks in allowed locations may defeat this protection in earlier versions of Deno.

Reporters

This vulnerability was reported by a number of analysts. Thanks to [email protected], [email protected], @leesh3288, and @cristianstaicu for their reports and analysis.

Record
JLSEC-2026-107
CVSS 3.1
9.0 CriticalCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
deno
crates.io
before 1.43.1
1.43.1
Deno_jll
Julia
before 2.0.0+0
2.0.0+0

History

History
RecordedChangedSources
publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2024-34346 is a high vulnerability (CVSS 8.5) in Deno, published May 7, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.37%, the 30th percentile. Fixed in deno 1.43.1.

References

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