Description
Impact
Elysia cookie can be overridden by prototype pollution , eg. __proto__
Sending cookie with the follows name can override cookie value:
__proto__=%7B%22injected%22%3A%22polluted%22%7D
Patches
Patched by 1.4.27
Workarounds
- Use t.Cookie validation to enforce validation value
- Prevent iterable over cookie if possible
Basic information
- Type
- reviewed
- Severity
- medium
- Advisory on GitHub
- Open advisory ↗
- Repository advisory
- Open repository advisory ↗
- Source code
- Browse source ↗
- Published (advisory)
- 2026-03-17 16:17:41 UTC
- Updated
- 2026-03-22 04:26:33 UTC
- GitHub reviewed
- 2026-03-17 16:17:41 UTC
- NVD published
- 2026-03-18
EPSS Score
| Score |
Percentile |
|
0.02%
|
4.75% |
CVSS Scores
| Base score |
Version |
Severity |
Vector |
|
6.5
|
3.1 |
—
|
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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:L)
- Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
- 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:L)
- Some sensitive info could get out, but not a total data dump.
- 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.
|
CWEs
| CWE id |
Name |
|
CWE-1321
|
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') |
Affected packages (1)
Vulnerable version ranges and first patched releases as published by GitHub.
| Ecosystem |
Package |
Vulnerable range |
First patched |
Vulnerable functions |
| npm |
elysia |
< 1.4.27 |
1.4.27 |
—
|
cvelogic
Threat Intelligence