CASCACascade Atlas

Evidence dossier

CVE-2021-41773

Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

Exploited in the wild (CISA KEV since Nov 3, 2021). NVD reports CVSS 3.1 9.8. Severity assessments differ within at least one CVSS version. EPSS estimates 100.0% exploit likelihood as of Jul 26, 2026.

84.9–91.3Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration "require all denied", these requests can succeed. If CGI scripts are also enabled for these aliased pathes, this could allow for remote code execution. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions. The fix in Apache HTTP Server 2.4.50 was found to be incomplete, see CVE-2021-42013.

State
PUBLISHED
Published
Oct 5, 2021
Updated
Oct 21, 2025
Evidence coverage
85%

Evidence chronology

What was known when

Download this view's receipt →
  1. Source dateSource date omittedFirst observed by CASCA
    apache

    Record text: Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

    Inspect raw assertion
    Field
    container
    Value
    Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    CISA-ADP

    Record text: CISA ADP Vulnrichment

    Inspect raw assertion
    Field
    container
    Value
    CISA ADP Vulnrichment
    Original evidence ↗
  3. Source dateSource date omittedFirst observed by CASCA
    CVE Program

    Record text: CVE Program Container

    Inspect raw assertion
    Field
    container
    Value
    CVE Program Container
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Apache HTTP Server Path Traversal Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Apache HTTP Server Path Traversal Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 99.99% probability · 99.99th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.999920000000; percentile 0.999860000000
    Original evidence ↗

Assessments differ

NVD9.8CVSS 3.1 · source date omitted
NVD4.3CVSS 2.0 · source date omitted
CVE Program source7.5CVSS 3.1 · source date omitted

Values are shown separately by source and CVSS version.

ExploitationCatalog member

CISA KEV · catalog date Nov 3, 2021 · first observed Jul 19, 2026

Exploit likelihood99.99%

FIRST EPSS · score date Jul 26, 2026 · 100th percentile · first observed Jul 27, 2026

SeverityAssessments differ

NVD · CVSS 3.1 · first observed Jul 19, 2026 · values shown separately below

Evidence detail

Source limits and decisions

Why each evidence state has this value

casca-unknown-reasons-v1
Exploitation statusEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Severity assessmentAssessments differ

Eligible assertions materially conflict and remain visible side by side.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Aug 27, 2026
Resolution
Resolve conflict
Affected productsSource-reported scope

The cited source assertion is retained while canonical product linkage remains open.

Revision
casca-factor-d-obligations-v1
Cutoff
Aug 27, 2026
Resolution
Resolve identity

Source comparison

Who said what

apacheOriginal assertion
Record text

Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

Inspect raw assertion
Field
container
Value
Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA-ADPIndependent enrichment
Record text

CISA ADP Vulnrichment

Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CVE ProgramDerivative copy
Record text

CVE Program Container

Inspect raw assertion
Field
container
Value
CVE Program Container
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Apache HTTP Server Path Traversal Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Apache HTTP Server Path Traversal Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

99.99% probability · 99.99th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.999920000000; percentile 0.999860000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
7Underlying assertions
4Canonical products
7Target assertions
0Constraint assertions

Grouped from 4 configuration nodes in this exact snapshot. Visual grouping is navigational; asset exposure and root cause require cited evidence.

Identity source boundaries
  • Cpe dictionary1,775,266 records · observed through 2026-07-21T06:45:29.809Z27d65b0f-b718-4b4f-bb79-c47c68d09dfa
  • Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z955dae73-7302-438b-aee1-058d7cc5d48e

5 scope groups

apache · source assertedApache Software FoundationApache HTTP ServerDirect source scope
Affected: Apache HTTP Server 2.4 2.4.49
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "Apache HTTP Server 2.4 2.4.49"}]
NVD CPE · APPLICATIONapachehttp_serverVulnerable target · 1 assertions
Version 2.4.49Canonical identity product-9ac1ed1c70311d36a45c72f8dd14128e1f8de18b347393d0fa18e946c202b58bLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:apache:http_server:2.4.49:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    b201cfb2-f626-4dd0-9f6a-dfe8f64203e2
NVD CPE · OPERATING SYSTEMfedoraprojectfedoraVulnerable target · 2 assertions
Version 34; Version 35Canonical identity product-c96c7662a6606ed7594747da3d7ba9ee3a9758ab11658f6a3f42616361472e47Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    1 · node/0 · match 1
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    80e516c0-98a4-4ade-b69f-66a772e2baaa
  2. cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    1 · node/0 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    a930e247-0b43-43cb-98ff-6ce7b8189835
NVD CPE · APPLICATIONnetappcloud_backupVulnerable target · 1 assertions
Version not applicableCanonical identity product-82c0ed89ab714a80f8d7ca4b0a7a5e6e1968a59a16c17a9f6a2a0a6a4757f6bfLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    3 · node/0 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    5c2089ee-5d7f-47ec-8ea5-0f69790564c4
NVD CPE · APPLICATIONoracleinstantis_enterprisetrackVulnerable target · 3 assertions
Version 17.1; Version 17.2; Version 17.3Canonical identity product-5d00280b7e61e03519c1b83650a5d87f654dd625a18111d908ab01d840aacb09Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    2 · node/0 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    82ea4ba7-c38b-4af3-8914-9e3d089ebdd4
  2. cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    2 · node/0 · match 1
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    b9c9bc66-fa5f-4774-9bda-7ab88e2839c4
  3. cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    2 · node/0 · match 2
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    7f69b9a5-f21b-4904-9f27-95c0f7a628e3

Affected-product evidence

Accepted scope and product mapping

4 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-b1377626da187dbea1eeb98f365c57a3dcbeccfdc2a7d3471e94ece7b6f88e55 · product-5d00280b7e61e03519c1b83650a5d87f654dd625a18111d908ab01d840aacb09

Source class
Nvd cpe vulnerable target
Assertions
3
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
27ffba34-e19e-40d9-9515-dc6f02035cd24e26ece7-7841-417e-a3d2-503d99b9b6fcb90567d0-5805-434f-a764-f13703ad1306
Mapping establishedEvidence supported

vendor-d1dcf2e2192106a1eb34744930a80b83005fa5d60195c923256e69ac39974aed · product-82c0ed89ab714a80f8d7ca4b0a7a5e6e1968a59a16c17a9f6a2a0a6a4757f6bf

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
3ddd6181-30b3-48d5-99f0-b36a1521d1e2
Mapping establishedEvidence supported

vendor-8771dac0ae5eeec984ca23e4bbe5a243fb7896ad7c1c4afc6acd3abe53fdd152 · product-9ac1ed1c70311d36a45c72f8dd14128e1f8de18b347393d0fa18e946c202b58b

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
aa5df54b-fa70-4512-97ad-41ad65efa49e
Mapping establishedEvidence supported

vendor-2d566b06907460b10e6e48c8544126e19f1d6df137983056edae8d0b51e34e45 · product-c96c7662a6606ed7594747da3d7ba9ee3a9758ab11658f6a3f42616361472e47

Source class
Nvd cpe vulnerable target
Assertions
2
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
00b1324e-6da5-43f3-8bc0-9186e53bf047e42a0e7d-299a-473b-af4e-c84f82ec70bc
Source-reported scopeSource-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Vendor specified only by source · Product specified only by source

Source class
Direct cve affected
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
91e0e00c-5236-4b97-b1b5-e170ccf38a85

Assessments

CVSS by origin

9.8
NVDCVSS 3.1 · role Primary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
4.3
NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:N/AC:M/Au:N/C:P/I:N/A:N
7.5
CVE Program sourceCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
7.5
CISA-ADPCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Direct CVE/CNA normalized decisions

7.5Priority eligible

CISA-ADP

CVSS 3.1 · Secondary · Independent enrichment · rank 2

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Validation
Valid match
Recomputed
7.5
Decision reason
Evidence supported
Policy
casca-direct-cvss-eligibility-v1

Assessments are retained side by side under closed precedence. Cascade never averages CVSS.

Evidence boundaries

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; remaining scope stays source-scoped.
  • NVD-carried upstream facts remain derivative; independent corroboration requires a separately authored source.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.
  • OSV aggregation and OSV-converted NVD material are not independent corroboration.
  • Red Hat facts are vendor assertions for the exact supplied products.
  • Nonmembership and not-yet-observed states are not proof of safety.