Next.js has a Cache poisoning vulnerability due to omission of the Vary header

Description

Summary

A cache poisoning issue in Next.js App Router >=15.3.0 and < 15.3.3 may have allowed RSC payloads to be cached and served in place of HTML, under specific conditions involving middleware and redirects. This issue has been fixed in Next.js 15.3.3.

Users on affected versions should upgrade immediately and redeploy to ensure proper caching behavior.

More details: CVE-2025-49005

Basic information

Type
reviewed
Severity
low
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2025-07-03 20:30:18 UTC
Updated
2025-07-03 21:49:02 UTC
GitHub reviewed
2025-07-03 20:30:18 UTC
NVD published
2025-07-03

EPSS Score

Score Percentile
0.17% 38.66%

CVSS Scores

Base score Version Severity Vector
3.7 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
npm next >= 15.3.0, < 15.3.3 15.3.3

References

cvelogic Threat Intelligence