CVE-2021-0268
An Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting') weakness in J-web of Juniper Networks Junos OS leads to buffer overflows, segment faults, or other impacts, which allows an attacker to modify the integrity of the device and exfiltration information from the device without authentication. The weakness can be exploited to facilitate cross-site scripting (XSS), cookie manipulation (modifying session cookies, stealing cookies) and more. This weakness can also be exploited by directing a user to a seemingly legitimate link from the affected site. The attacker requires no special access or permissions to the device to carry out such attacks. This issue affects: Juniper Networks Junos OS: 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S5; 18.3 versions prior to 18.3R2-S4, 18.3R3-S3; 18.4 versions prior to 18.4R2-S5, 18.4R3-S3; 19.1 versions prior to 19.1R2-S2, 19.1R3-S2; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R3; 19.4 versions prior to 19.4R1-S3, 19.4R2, 19.4R3; 20.1 versions prior to 20.1R1-S2, 20.1R2. This issue does not affect Juniper Networks Junos OS versions prior to 18.1R1.
Scoring
- Severity
- HIGH
- CVSS base score
- 8.8
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:L
- EPSS probability
- 0.27%
- CWE
- CWE-113, CWE-120, CWE-79
- Published
- 2021-04-22
- Last modified
- 2026-03-13
Affected products
- Juniper Networks Junos OS
- Juniper Networks Junos OS
- Juniper Networks Junos OS
- Juniper Networks Junos OS
- Juniper Networks Junos OS
- Juniper Networks Junos OS
- Juniper Networks Junos OS
- Juniper Networks Junos OS
Weakness type
Related vulnerabilities
- CVE-2026-34520 — AIOHTTP: C parser (llhttp) accepts null bytes and control characters in response header values - header injection / security bypass
- CVE-2025-53007 — arduino-esp32 vulnerable to CRLF injection in WebServer.cpp
- CVE-2024-52875 — An issue was discovered in GFI Kerio Control 9.2.5 through 9.4.5. The dest GET parameter passed to the /nonauth/addCertE
- CVE-2025-61689 — HTTP.jl vulnerable to Header injection/Response splitting via header construction.
- CVE-2025-53094 — ESPAsyncWebServer Vulnerable to CRLF Injection in AsyncWebHeader.cpp
- CVE-2025-59151 — Pi-hole Admin Interface vulnerable to HTTP response header injection via CRLF injection
- CVE-2026-67289 — FreeRDP before 3.29.0 HTTP Proxy Request Injection via Redirection
- CVE-2023-32708 — HTTP Response Splitting via the ‘rest’ SPL Command