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Full vulnerability report · 2006
CVE-2006-0743High confidence

Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory corruption and termination) via unknown vectors

Unknown · Unknown

5.0MediumCVSS 2.0
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 6.37% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Open-source package ranges2 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
NuGetlog4netECOSYSTEM: introduced 0; fixed 1.2.101.2.10OSV record ↗aggregator derived · 9 Feb 2024
nugetlog4net<= 1.2.91.2.10GitHub advisory ↗github reviewed aggregator · 9 Feb 2024
Optional official sources

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

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

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-2022-3735

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 actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory corruption and termination) via unknown vectors.

What

Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory corruption and termination) via unknown vectors.

Why

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

How

An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may disrupt the affected service.

What

Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory corruption and termination) via unknown vectors.

Why

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

How

An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. 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
the affected interface → Use of Externally-Controlled Format String → disrupt the affected service
Attack surface
Unspecified
Privileges required
None: unauthenticated exploitation is possible
User interaction
Not stated in the selected CVSS metric
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not stated in the selected CVSS metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-134 ↗

CWE-134: Use of Externally-Controlled Format String. The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
AV:N/AC:L/Au:N/C:N/I:N/A:P
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.
UnauthenticatedDenial of serviceCWE-134
A

Official authority intelligence

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

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
n/a: 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.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 9 Mar 2006 · Last source change 7 Aug 2024, 16:48 UTC · CWE-134 · Use of Externally-Controlled Format String

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-13
European sourceENISA EUVD · EUVD-2022-3735
Product sourceUnavailable
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
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

What changed after publication

View recent updates ↗
  1. ENISA EUVD mappingEUVD-2022-3735 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2022-3735"}
    ENISA EUVD ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: issues.apache.org/LOG4NET-67; added patch: secunia.com/19241; removed vendor advisory: novell.com/2006_26_sr.html; 3 further additions.
    Before
    vendor advisory: novell.com/2006_26_sr.html
    After
    patch: issues.apache.org/LOG4NET-67 · patch: secunia.com/19241 · remediation: secunia.com/19241 · 2 more references
    secunia.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    n/a: n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    n/a: 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.
    CNA ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    secunia.com ↗
  5. SeveritySeverity changed from Unknown to Medium.
    Before
    Unknown
    After
    Medium
    NIST NVD ↗
  6. CVSS scoreCVSS score changed from not recorded to 5.0 (CVSS 2.0 · NIST NVD · AV:N/AC:L/Au:N/C:N/I:N/A:P).
    Before
    not recorded
    After
    5.0 (CVSS 2.0 · NIST NVD · AV:N/AC:L/Au:N/C:N/I:N/A:P)
    NIST NVD ↗
  7. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
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-2022-3735↗CVE authority or vendor reference↗Vendor advisory↗Patch or update reference↗Patch or update 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-2006-0743 · cve.blacktree.nl