CVE-2026-3634
Redhat Enterprise Linux 10.0 … 9.0
Raw vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:LSummary
CVE-2026-3634 is a low-severity CRLF Injection (CWE-93) vulnerability in Redhat Enterprise Linux. Its CVSS base score is 3.9 (Low).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12561
Vulnerability Data
A flaw was found in libsoup. An attacker controlling the value used to set the Content-Type header can inject a Carriage Return Line Feed (CRLF) sequence due to improper input sanitization in the `soup_message_headers_set_content_type()` function. This vulnerability allows for the…
more
injection of arbitrary header-value pairs, potentially leading to HTTP header injection and response splitting attacks.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CRLF injection in HTTP header handling directly enables exploitation of public-facing web applications via response splitting.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires validation and sanitization of untrusted input (such as Content-Type values) before it is used to construct HTTP headers, blocking CRLF injection at the source.
Enforces policy-based information flow rules on HTTP message construction, preventing untrusted data from altering header structure or producing response-splitting sequences.
Boundary-protection mechanisms can inspect and filter outgoing HTTP responses to drop or sanitize malformed headers containing injected CRLF sequences.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input neutralization and validation to block CRLF injection.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect CRLF flaws but does not itself implement the neutralization.
Secure development lifecycle mandates input validation and output encoding that directly prevents CRLF injection.
Application security requirements include rules for neutralizing special characters such as CRLF in inputs.
Secure architecture principles encourage safe handling of untrusted data but do not prescribe specific CRLF controls.
Secure coding standards explicitly require neutralization of CRLF sequences, fully addressing this weakness.