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🛡️ JLSEC-2026-107 — deno-jll (CVE-2024-34346)

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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]](mailto:[email protected]), [[email protected]](mailto:[email protected]), @leesh3288, and @cristianstaicu for their reports and analysis.

How this vulnerability can be exploited

This issue can be reached from an adjacent network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

  • Attack vector: Adjacent network — the attacker has to sit on the same local or logical network.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Changed — a successful attack reaches components beyond the vulnerable one.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

JLSEC-2026-107 is recorded against 1 package.

  • deno-jll

Timeline and source

Published on 14 April 2026 and last revised on 18 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
nvd.nist.gov (Web)

Other advisories for this package

deno-jll has other advisories on record. If you are patching this one, these are worth checking on the same host:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-04-14
Updated 2026-08-20
Modified 2026-07-18
Fix URL N/A

Affected Packages

Software From version Fixed in
deno-jll — —

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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