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Enterprise LinuxOperating system · Redhat

CVE-2026-1801

MEDIUM · 6.5 CVSS v3.1 Published 2026-02-03
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A flaw was found in libsoup, an HTTP client/server library. This HTTP Request Smuggling vulnerability arises from non-RFC-compliant parsing in the soup_filter_input_stream_read_line() logic, where libsoup accepts malformed chunk headers, such as lone line feed (LF) characters instead of the required carriage return and line feed (CRLF). A remote attacker can exploit this without authentication or user interaction by sending specially crafted chunked requests. This allows libsoup to parse and process multiple HTTP requests from a single network message, potentially leading to information disclosure.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

libsoup fails to properly validate chunked transfer encoding headers, accepting malformed lone LF characters instead of requiring RFC-compliant CRLF sequences in soup_filter_input_stream_read_line(). This allows HTTP Request Smuggling where an attacker can embed multiple requests within a single network message by manipulating chunk boundaries, potentially causing the server to interpret and process unintended requests and disclose information.

MitigationApply the vendor patch to libsoup that enforces proper CRLF validation in chunk header parsing, then update all dependent applications to the patched library version.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Enterprise LinuxOperating system
Affected:= 6.0= 7.0= 8.0= 9.0= 10.0
LibsoupApplication
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if libsoup is installed
    Run 'rpm -qa | grep libsoup' on RHEL systems, or check for libsoup shared library files (lib/libsoup*.so*) in the system
    Affected if libsoup packages or library files are found on the system
  2. Determine libsoup version
    Run 'rpm -q libsoup' or 'dpkg -l libsoup' to get the exact version number installed
    Affected if Any version of libsoup is installed, since all versions are affected according to the CVE data
  3. Identify applications using libsoup as an HTTP server
    Check running processes for applications known to depend on libsoup for HTTP serving, or review application dependencies (rpm -qR libsoup or checking application documentation)
    Affected if Applications using libsoup for HTTP server functionality are running or configured
  4. Verify if chunked transfer encoding is in use
    Examine HTTP traffic logs or capture network traffic to identify if incoming HTTP requests use Transfer-Encoding: chunked header
    Affected if Chunked transfer encoding is being processed by libsoup-based servers
  5. Inspect HTTP request headers for malformed chunk headers
    Review HTTP access logs or captured network traffic for chunked requests containing lone LF (\n) characters instead of proper CRLF (\r\n) sequences in chunk headers
    Affected if Malformed chunked requests with lone LF characters are being accepted and processed without rejection

The environment is affected if libsoup is installed and any application using it serves HTTP requests that may process chunked transfer encoding, since all versions of libsoup accept the RFC-noncompliant lone LF in chunk headers.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor patch to libsoup that enforces proper CRLF validation in chunk header parsing, then update all dependent applications to the patched library version.

Fix this in Enterprise Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-1801 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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