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NVD / CVE Program· CNA redhat

CVE-2026-1801: Libsoup: libsoup: http request smuggling via malformed chunk headers

Noroxi assessment

Priority: Monitor (action score 26/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.42% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: libsoup3 (Debian:14) 3.6.5-8; libsoup2 (openSUSE:Tumbleweed) 2.74.3-21.1; libsoup2 (SUSE:Linux Enterprise Micro 5.3) 2.74.2-150400.3.37.1.

Low priority for now. Upgrade to libsoup3 (Debian:14) 3.6.5-8; libsoup2 (openSUSE:Tumbleweed) 2.74.3-21.1; libsoup2 (SUSE:Linux Enterprise Micro 5.3) 2.74.2-150400.3.37.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 6.5 · v3.1—Proof of concept Fix available
Published
Feb 3, 2026
Updated
Jun 17, 2026
EPSS
0.4% · 36th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
6.5
CNA · redhat
5.3
1.2 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
gnomelibsoup
redhatenterprise linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • gnome libsoupall versions
  • redhat enterprise linux10.0
  • redhat enterprise linux6.0
  • redhat enterprise linux7.0
  • redhat enterprise linux8.0
  • redhat enterprise linux9.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • Red Hat Red Hat Enterprise Linux 10

    • all versionsaffected

  • Red Hat Red Hat Enterprise Linux 6

    • all versionsaffected

  • Red Hat Red Hat Enterprise Linux 7

    • all versionsaffected

  • Red Hat Red Hat Enterprise Linux 8

    • all versionsaffected

  • Red Hat Red Hat Enterprise Linux 9

    • all versionsaffected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12libsoup2.4from 0—
Debian:12libsoup3from 0—
Debian:14libsoup3before 3.6.5-83.6.5-8
openSUSE:Tumbleweedlibsoup2before 2.74.3-21.12.74.3-21.1
SUSE:Linux Enterprise Micro 5.3libsoup2before 2.74.2-150400.3.37.12.74.2-150400.3.37.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7libsoupbefore 3.4.4-150600.3.47.13.4.4-150600.3.47.1
SUSE:Linux Enterprise Module for Basesystem 15 SP7libsoup2before 2.74.3-150600.4.36.12.74.3-150600.4.36.1
SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5libsoupbefore 2.62.2-5.43.12.62.2-5.43.1
SUSE:Linux Micro 6.0libsoupbefore 3.4.2-16.13.4.2-16.1
SUSE:Linux Micro 6.1libsoupbefore 3.4.4-slfo.1.1_10.13.4.4-slfo.1.1_10.1

Same product

gnome: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-2885An exploitable stack based buffer overflow vulnerability exists in the GNOME libsoup 2.58.
    46Plan
  • CVE-2019-17266libsoup from versions 2.65.1 until 2.68.1 have a heap-based buffer over-read because soup_ntlm_parse_challenge() in soup-auth-ntlm.c does no
    40Plan
  • CVE-2018-12910The get_cookies function in soup-cookie-jar.c in libsoup 2.63.2 allows attackers to have unspecified impact via an empty hostname.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-1536Jan 28, 2026 · Libsoup: libsoup: http header injection or response splitting via crlf injection in content-disposition header
    21Monitor
  • ← EarlierCVE-2026-1539Jan 28, 2026 · Libsoup: libsoup: credential leakage via http redirects
    23Monitor
  • Later →CVE-2026-2443Feb 13, 2026 · Libsoup: out-of-bounds read in libsoup handle_partial_get() leading to heap information disclosure
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:libsoup33.6.5-8 · Debian:14Package registry (OSV)
opensuse:libsoup22.74.3-21.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:libsoup3.4.2-16.1 · SUSE:Linux Micro 6.0Package registry (OSV)
suse:libsoup22.74.3-150600.4.36.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP7Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-08-29

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+206 d
  3. TodayOct 26, 2026+265 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2024-52530449 days apartGNOME libsoup before 3.6.0 allows HTTP request smuggling in some configurations because '\0' characters at the end of header names are ignor
    30Monitor
  • CVE-2026-66338171 days apartLibsoup: libsoup: http request smuggling via permissive chunk-size parsing in soup_body_input_stream_read_chunked()
    28Monitor
  • CVE-2026-270879 days apartLibsoup: libsoup: http request smuggling via duplicate content-length headers
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-363242 days apartLibsoup: libsoup: http smuggling and server-side request forgery via malformed hostnames
    22Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records