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Full vulnerability report · 2025
CVE-2025-9648High confidence

Denial of Service in CivetWeb

CivetWeb · CivetWeb

8.7HighCVSS 4.0
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivecivetwebUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 8 Sept 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2025-9648 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitycivetweb: Denial of Service in CivetWeb
12 fixed

The vendor explicitly identifies these products or versions as containing the fix.

  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:0ba8b652771a517a5c724bc91bbca265a8e86efdd2e83b504c8fb309715a3758_s390x as a component of Red Hat Advanced Cluster Security 4.7
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:271dd3bfa99f1043d3ee885764fda7d3ba89c232025c1d3ad7fe45324f47473d_arm64 as a component of Red Hat Advanced Cluster Security 4.7
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:488e7716dc50df623f9088ee36120266d4db2637e2d2ce89810f1fdd8f2161f0_amd64 as a component of Red Hat Advanced Cluster Security 4.7
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:e3444345f04c1569ec97530ddd6b6e4ccd38a2887d500054ac93f76f54c07aa8_ppc64le as a component of Red Hat Advanced Cluster Security 4.7
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:4e13827b69f9e8be0771e36046c60ec35522b8ab6b93215687fbda51ba928afc_arm64 as a component of Red Hat Advanced Cluster Security 4.8
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:5a07faace45b9bb6cafd88113902b51b3753ffdf777eba47e91f009cfadec528_amd64 as a component of Red Hat Advanced Cluster Security 4.8
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d32b4648796a4cb84487b87c122e881b0b44120cbc4487644de3d282e04b1696_s390x as a component of Red Hat Advanced Cluster Security 4.8
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:efd818242280438cd837dbb0d98de6e20f8b833e34e057ef58914cd58c4ecbf7_ppc64le as a component of Red Hat Advanced Cluster Security 4.8
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:59dd5e6cb07cf38e499d909e1c07969db6a750a941051a4f6f7c2fb11ec16cd4_ppc64le as a component of Red Hat Advanced Cluster Security 4.9
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:66ec9c8c40011633c6f62dfb1b0d238ac1dac8aa694c6bccc67d55bb3bb058da_arm64 as a component of Red Hat Advanced Cluster Security 4.9
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:bb30abe978ff9a89ef5f954d26a2536a40327f2d40bc58a75287eeb9a17e9cca_s390x as a component of Red Hat Advanced Cluster Security 4.9
  • registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d1097b8171d9bd2bc615eee808f636a23a6851ded7b9905262fadddb80fcd2f5_amd64 as a component of Red Hat Advanced Cluster Security 4.9
Summary
A denial of service flaw has been discovered in CivetWeb. The mg_handle_form_request function allows attackers to trigger a denial of service (DoS) condition by sending a specially crafted HTTP POST request containing a null byte in the payload. The server enters an infinite loop during form data parsing as a result. Multiple malicious requests will result in complete CPU exhaustion and render the service unresponsive to further requests.
Remediation
If you are using an earlier version of RHACS, you are advised to upgrade to the version of RHACS mentioned in the synopsis and release notes in order to take advantage of the enhancements, bug fixes, and/or security patches in the release.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-31569

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

A vulnerability in the CivetWeb library's function mg_handle_form_request allows remote attackers to trigger a denial of service (DoS) condition. By sending a specially crafted HTTP POST request containing a null byte in the payload, the server enters an infinite loop during form data parsing. Multiple malicious requests will result in complete CPU exhaustion and render the service unresponsive to further requests. This issue was fixed in commit 782e189. This issue affects only the library, standalone executable pre-built by vendor is not affected.

What

A vulnerability in the CivetWeb library's function mg_handle_form_request allows remote attackers to trigger a denial of service (DoS) condition. By sending a specially crafted HTTP POST request containing a null byte in the payload, the server enters an infinite loop during form data parsing. Multiple malicious requests will result in complete CPU exhaustion and render the service unresponsive to further requests. This issue was fixed in commit 782e189. This issue affects only the library, standalone executable pre-built by vendor is not affected.

Why

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes NUL characters or null bytes when they are sent to a downstream component.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

A vulnerability in the CivetWeb library's function mg_handle_form_request allows remote attackers to trigger a denial of service (DoS) condition. By sending a specially crafted HTTP POST request containing a null byte in the payload, the server enters an infinite loop during form data parsing. Multiple malicious requests will result in complete CPU exhaustion and render the service unresponsive to further requests. This issue was fixed in commit 782e189. This issue affects only the library, standalone executable pre-built by vendor is not affected.

Why

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes NUL characters or null bytes when they are sent to a downstream component.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Neutralization of Null Byte or NUL Character → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-158 ↗

CWE-158: Improper Neutralization of Null Byte or NUL Character. The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes NUL characters or null bytes when they are sent to a downstream component.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-158
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-W-2025-2668Red Hat Enterprise Linux (CivetWeb library): Schwachstelle ermöglicht Denial of Service

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Red Hat Enterprise Linux ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory
CERT Polska · Polish · CVE-2025-9648CERT Polska w social mediach

CERT Polska otrzymał zgłoszenie o podatności w oprogramowaniu CivetWeb i koordynował proces ujawniania informacji. Podatność CVE-2025-9648 : Podatność w funkcji mg_handle_form_request biblioteki CivetWeb umożliwia zdalnym atakującym przeprowadzenie ataku DoS na serwer. Poprzez przesłanie specjalnie spreparowanego żądania HTTP POST zawierającego bajt zerowy (null byte) w treści, serwer wchodzi w nieskończoną pętlę podczas parsowania danych formularza. Wysłanie wielu takich złośliwych żądań prowadzi do całkowitego zużycia zasobów CPU i sprawia, że usługa przestaje odpowiadać na kolejne żądania. Problem został rozwiązany w commicie 782e189. Problem dotyczy wyłącznie biblioteki, udostępniany przez producenta plik wykonywalny nie jest podatny na tę lukę.

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
1.08 < 1.10; 1.10 ≤ 1.16
Fixed
registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:0ba8b652771a517a5c724bc91bbca265a8e86efdd2e83b504c8fb309715a3758_s390x as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:271dd3bfa99f1043d3ee885764fda7d3ba89c232025c1d3ad7fe45324f47473d_arm64 as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:488e7716dc50df623f9088ee36120266d4db2637e2d2ce89810f1fdd8f2161f0_amd64 as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:e3444345f04c1569ec97530ddd6b6e4ccd38a2887d500054ac93f76f54c07aa8_ppc64le as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:4e13827b69f9e8be0771e36046c60ec35522b8ab6b93215687fbda51ba928afc_arm64 as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:5a07faace45b9bb6cafd88113902b51b3753ffdf777eba47e91f009cfadec528_amd64 as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d32b4648796a4cb84487b87c122e881b0b44120cbc4487644de3d282e04b1696_s390x as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:efd818242280438cd837dbb0d98de6e20f8b833e34e057ef58914cd58c4ecbf7_ppc64le as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:59dd5e6cb07cf38e499d909e1c07969db6a750a941051a4f6f7c2fb11ec16cd4_ppc64le as a component of Red Hat Advanced Cluster Security 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:66ec9c8c40011633c6f62dfb1b0d238ac1dac8aa694c6bccc67d55bb3bb058da_arm64 as a component of Red Hat Advanced Cluster Security 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:bb30abe978ff9a89ef5f954d26a2536a40327f2d40bc58a75287eeb9a17e9cca_s390x as a component of Red Hat Advanced Cluster Security 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d1097b8171d9bd2bc615eee808f636a23a6851ded7b9905262fadddb80fcd2f5_amd64 as a component of Red Hat Advanced Cluster Security 4.9
Action
If you are using an earlier version of RHACS, you are advised to upgrade to the version of RHACS mentioned in the synopsis and release notes in order to take advantage of the enhancements, bug fixes, and/or security patches in the release.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 29 Sept 2025 · Last source change 29 Sept 2025, 12:53 UTC · CWE-158 · Improper Neutralization of Null Byte or NUL Character

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-31569
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    Fixed: registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:0ba8b652771a517a5c724bc91bbca265a8e86efdd2e83b504c8fb309715a3758_s390x as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:271dd3bfa99f1043d3ee885764fda7d3ba89c232025c1d3ad7fe45324f47473d_arm64 as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:488e7716dc50df623f9088ee36120266d4db2637e2d2ce89810f1fdd8f2161f0_amd64 as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:e3444345f04c1569ec97530ddd6b6e4ccd38a2887d500054ac93f76f54c07aa8_ppc64le as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:4e13827b69f9e8be0771e36046c60ec35522b8ab6b93215687fbda51ba928afc_arm64 as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:5a07faace45b9bb6cafd88113902b51b3753ffdf777eba47e91f009cfadec528_amd64 as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d32b4648796a4cb84487b87c122e881b0b44120cbc4487644de3d282e04b1696_s390x as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:efd818242280438cd837dbb0d98de6e20f8b833e34e057ef58914cd58c4ecbf7_ppc64le as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:59dd5e6cb07cf38e499d909e1c07969db6a750a941051a4f6f7c2fb11ec16cd4_ppc64le as a component of Red Hat Advanced Cluster Security for Kubernetes 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:66ec9c8c40011633c6f62dfb1b0d238ac1dac8aa694c6bccc67d55bb3bb058da_arm64 as a component of Red Hat Advanced Cluster Security for Kubernetes 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:bb30abe978ff9a89ef5f954d26a2536a40327f2d40bc58a75287eeb9a17e9cca_s390x as a component of Red Hat Advanced Cluster Security for Kubernetes 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d1097b8171d9bd2bc615eee808f636a23a6851ded7b9905262fadddb80fcd2f5_amd64 as a component of Red Hat Advanced Cluster Security for Kubernetes 4.9
    After
    Fixed: registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:0ba8b652771a517a5c724bc91bbca265a8e86efdd2e83b504c8fb309715a3758_s390x as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:271dd3bfa99f1043d3ee885764fda7d3ba89c232025c1d3ad7fe45324f47473d_arm64 as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:488e7716dc50df623f9088ee36120266d4db2637e2d2ce89810f1fdd8f2161f0_amd64 as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:e3444345f04c1569ec97530ddd6b6e4ccd38a2887d500054ac93f76f54c07aa8_ppc64le as a component of Red Hat Advanced Cluster Security 4.7; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:4e13827b69f9e8be0771e36046c60ec35522b8ab6b93215687fbda51ba928afc_arm64 as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:5a07faace45b9bb6cafd88113902b51b3753ffdf777eba47e91f009cfadec528_amd64 as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d32b4648796a4cb84487b87c122e881b0b44120cbc4487644de3d282e04b1696_s390x as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:efd818242280438cd837dbb0d98de6e20f8b833e34e057ef58914cd58c4ecbf7_ppc64le as a component of Red Hat Advanced Cluster Security 4.8; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:59dd5e6cb07cf38e499d909e1c07969db6a750a941051a4f6f7c2fb11ec16cd4_ppc64le as a component of Red Hat Advanced Cluster Security 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:66ec9c8c40011633c6f62dfb1b0d238ac1dac8aa694c6bccc67d55bb3bb058da_arm64 as a component of Red Hat Advanced Cluster Security 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:bb30abe978ff9a89ef5f954d26a2536a40327f2d40bc58a75287eeb9a17e9cca_s390x as a component of Red Hat Advanced Cluster Security 4.9; registry.redhat.io/advanced-cluster-security/rhacs-collector-rhel8@sha256:d1097b8171d9bd2bc615eee808f636a23a6851ded7b9905262fadddb80fcd2f5_amd64 as a component of Red Hat Advanced Cluster Security 4.9
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2025-31569↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-9648 · cve.blacktree.nl