CVE-2021-25761
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
- Record
CVE-2021-25761- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-326
- Updated
- 2026-11-02
CVE List No score
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
- Record
CVE-2021-25761- Updated
- 2026-11-02
EUVDEUVD-2021-12644 No score
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
- Record
EUVD-2021-12644- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-w76f-c56x-cr72
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
- Record
GHSA-w76f-c56x-cr72- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-327
- Updated
- 2026-11-02
OSV
In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.
- Record
CVE-2021-25761- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-25761 is a medium vulnerability (CVSS 5.3) in Jetbrains Ktor, published February 3, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.55%, the 46th percentile. No source names a fixed version.