CVE-2025-48888: deno Auth Bypass — Exploit & Fix

Description

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Starting in version 1.41.3 and prior to versions 2.1.13, 2.2.13, and 2.3.2, `deno run --allow-read --deny-read main.ts` results in allowed, even though 'deny' should be stronger. The result is the same with all global unary permissions given as `--allow-* --deny-*`. This only affects a nonsensical combination of flags, so there shouldn't be a real impact on the userbase. Users may upgrade to version 2.1.13, 2.2.13, or 2.3.2 to receive a patch.

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CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Weakness Type (CWE)

CWE-863 Incorrect Authorization

Affected Products

Vendor	Product	Versions
deno	deno	1.41.3 — 2.1.13
deno	deno	2.2.0 — 2.2.13
deno	deno	2.3.0 — 2.3.2

References

Advisories & Patches

https://github.com/denoland/deno/commit/2f0fae9d9071dcaf0a689bc7097584b1b9ebc8db https://github.com/denoland/deno/commit/9d665572d3cd39f997e29e6daac7c1102fc5c04f https://github.com/denoland/deno/commit/ef315b56c26c9ef5f25284a5100d2ed525a148cf https://github.com/denoland/deno/pull/22894 https://github.com/denoland/deno/pull/29213 https://github.com/denoland/deno/security/advisories/GHSA-xqxc-x6p3-w683 https://github.com/denoland/deno/security/advisories/GHSA-xqxc-x6p3-w683

Exploits

https://github.com/denoland/deno/security/advisories/GHSA-xqxc-x6p3-w683 https://github.com/denoland/deno/security/advisories/GHSA-xqxc-x6p3-w683

Frequently Asked Questions

What is CVE-2025-48888? +

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Starting in version 1.41.3 and prior to versions 2.1.13, 2.2.13, and 2.3.2, `deno run --allow-read --deny-read main.ts` results in allowed, even though 'deny' should be stronger. The result is the same with all global unary permissions given as `--allow-* --deny-*`. This only affects a nonsensical combination of flags, so there shouldn't be a real impact on the userbase. Users may upgrade to version 2.1.13, 2.2.13, or 2.3.2 to receive a patch. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2025-48888? +

CVE-2025-48888 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-48888? +

CVE-2025-48888 affects products from deno, specifically: deno. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-48888? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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