Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.91% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2023
CVE-2023-24021High confidence
n/a — Improper Null Termination
Unknown · Unknown
7.5HighCVSS 3.1
Within 7 days
Patch availableHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
4 package statesRelease-specific package status
Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
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.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | modsecurity-apache | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.7-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | modsecurity-apache | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.7-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | modsecurity-apache | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.7-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | modsecurity-apache | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.9.7-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative 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.
CVE-2023-24021 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitymodsecurity: lacking the complete content in FILES_TMP_CONTENT leads to web application firewall bypass
The vendor explicitly identifies these products as affected by this CVE.
- mod_security-mlogc as a component of Red Hat Enterprise Linux 7
- mod_security.src as a component of Red Hat Enterprise Linux 7
- mod_security as a component of Red Hat Enterprise Linux 8
- mod_security-mlogc as a component of Red Hat Enterprise Linux 8
- mod_security.src as a component of Red Hat Enterprise Linux 8
- mod_security as a component of Red Hat Enterprise Linux 9
- mod_security-mlogc as a component of Red Hat Enterprise Linux 9
- mod_security.src as a component of Red Hat Enterprise Linux 9
- httpd24-mlogc as a component of Red Hat Software Collections
- httpd24-mod_security.src as a component of Red Hat Software Collections
- Summary
- A vulnerability was found in ModSecurity. This issue occurs when FILES_TMP_CONTENT lacks complete content, which can lead to a Web Application Firewall bypass.
- Remediation
- Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available01
What, why and how
Incorrect handling of '\0' bytes in file uploads in ModSecurity before 2.9.7 may allow for Web Application Firewall bypasses and buffer over-reads on the Web Application Firewall when executing rules that read the FILES_TMP_CONTENT collection.
What
Incorrect handling of '\0' bytes in file uploads in ModSecurity before 2.9.7 may allow for Web Application Firewall bypasses and buffer over-reads on the Web Application Firewall when executing rules that read the FILES_TMP_CONTENT collection.
Why
The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Incorrect handling of '\0' bytes in file uploads in ModSecurity before 2.9.7 may allow for Web Application Firewall bypasses and buffer over-reads on the Web Application Firewall when executing rules that read the FILES_TMP_CONTENT collection.
Why
The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 Null Termination → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-170 ↗
CWE-170: Improper Null Termination. The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NCommon Vulnerability Scoring System 3.1: 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.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.IHighIntegrity impact: A successful attack can cause a major loss.ANoneAvailability impact: 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.
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
- mod_security-mlogc as a component of Red Hat Enterprise Linux 7
- mod_security.src as a component of Red Hat Enterprise Linux 7
- mod_security as a component of Red Hat Enterprise Linux 8
- mod_security-mlogc as a component of Red Hat Enterprise Linux 8
- mod_security.src as a component of Red Hat Enterprise Linux 8
- mod_security as a component of Red Hat Enterprise Linux 9
- mod_security-mlogc as a component of Red Hat Enterprise Linux 9
- mod_security.src as a component of Red Hat Enterprise Linux 9
- httpd24-mlogc as a component of Red Hat Software Collections
- httpd24-mod_security.src as a component of Red Hat Software Collections
- Fixed
- jbcs-httpd24-mod_security-0:2.9.3-29.el7jbcs.src as a component of Red Hat JBoss Core Services on RHEL 7 Server
- jbcs-httpd24-mod_security-0:2.9.3-29.el7jbcs.x86_64 as a component of Red Hat JBoss Core Services on RHEL 7 Server
- jbcs-httpd24-mod_security-debuginfo-0:2.9.3-29.el7jbcs.x86_64 as a component of Red Hat JBoss Core Services on RHEL 7 Server
- jbcs-httpd24-mod_security-0:2.9.3-29.el8jbcs.src as a component of Red Hat JBoss Core Services on RHEL 8
- jbcs-httpd24-mod_security-0:2.9.3-29.el8jbcs.x86_64 as a component of Red Hat JBoss Core Services on RHEL 8
- jbcs-httpd24-mod_security-debuginfo-0:2.9.3-29.el8jbcs.x86_64 as a component of Red Hat JBoss Core Services on RHEL 8
- Action
- Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
- 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 20 Jan 2023 · Last source change 2 Apr 2025, 16:18 UTC · CWE-170 · Improper Null Termination
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2023-28085
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCISA ADP
NVD statusNVD modified after enrichment
Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- n/a · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- n/a · Fixed: Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
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.