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CVE Record

CVE-2025-4476: Libsoup: null pointer dereference in libsoup may lead to denial of service

A denial-of-service vulnerability has been identified in the libsoup HTTP client library. This flaw can be triggered when a libsoup client receives a 401 (Unauthorized) HTTP response containing a specifically crafted domain parameter within the WWW-Authenticate header. Processing this malformed header can lead to a crash of the client application using libsoup. An attacker could exploit this by setting up a malicious HTTP server. If a user's application using the vulnerable libsoup library connects to this malicious server, it could result in a denial-of-service. Successful exploitation requires tricking a user's client application into connecting to the attacker's malicious server.

MediumCVSS 4.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2025-4476 can crash applications that use libsoup when they process a malformed authentication header from a server. It does not expose data or change systems, but it can interrupt affected client applications. The attacker must get the application to connect to a malicious server.

Executive priority

Handle through normal patch management, with higher priority for systems where business workflows depend on libsoup-based clients reaching external servers. This is a service-disruption risk, not a confidentiality or integrity issue based on the provided sources.

Technical view

libsoup can hit a null pointer dereference while handling a 401 Unauthorized response with a crafted WWW-Authenticate domain parameter. Red Hat marks libsoup/libsoup3 on RHEL 8, 9, and 10 as affected, with RHEL 6 and 7 status unknown in the bundle. CVSS is 4.3, availability impact only.

Likely exposure

Exposure is most likely where RHEL systems run applications using libsoup or libsoup3 as an HTTP client and those applications connect to user-controlled or untrusted servers. Systems that only host HTTP services, or do not use libsoup-based clients, are less likely to be exposed.

Exploitation context

The bundle does not show known active exploitation, and KEV is false. Exploitation requires user interaction: a vulnerable client application must connect to an attacker-controlled server that returns the malformed 401 authentication header.

Researcher notes

The public bundle supports CWE-476 and a network-triggered client crash condition. It does not provide fixed versions, confirmed exploit activity, or complete lifecycle status for all listed RHEL versions. Avoid overstating exploitability beyond the malicious-server connection requirement.

Mitigation direction

  • Check Red Hat and GNOME guidance for fixed libsoup or libsoup3 packages.
  • Prioritize updates on RHEL 8, 9, and 10 systems running libsoup-based clients.
  • Limit vulnerable applications from connecting to untrusted or user-supplied HTTP endpoints where feasible.
  • Monitor vendor advisories because the bundle does not name fixed versions.

Validation and detection

  • Inventory applications and packages using libsoup or libsoup3.
  • Map affected systems to RHEL 8, 9, and 10 first.
  • Treat RHEL 6 and 7 status as unresolved until vendor guidance confirms impact.
  • Review crash reports for libsoup-based clients after HTTP 401 responses.
  • Track the linked Red Hat Bugzilla and GNOME issue for remediation details.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-476: Exact CWE lookup

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cve · low confidence lookup

CVE-2025-4476 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.3 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
5Timeline events
1ADP providers
5Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
4.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L2.81.4redhat

Vulnerability scoring details

Base CVSS 3.1 score

4.3Medium
CVSS 3.1 vector shape for CVE-2025-4476Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timelineredhat

    Made public.

  2. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  3. Source timelineredhat

    Reported to Red Hat.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Unknown vendorlibsouplibsoup, 0unaffected
Red HatRed Hat Enterprise Linux 10libsoup3affected
Red HatRed Hat Enterprise Linux 6libsoupunknown
Red HatRed Hat Enterprise Linux 7libsoupunknown
Red HatRed Hat Enterprise Linux 8libsoupaffected
Red HatRed Hat Enterprise Linux 9libsoupaffected
Weakness

CWE details

CWE-476

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-476 · source CWE mapping

NULL Pointer Dereference

NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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