The Microsoft .NET forms authentication capability for ASP.NET allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) "\" (backslash) or (2) "%5C" (encoded backslash), aka "Path Validation Vulnerability."
CVE-2004-0847
CRITICALNVD 9.89.8WeaponizedEG-KEV Tier 2: WeaponizedEG-KEV is EchelonGraph's own tiering of exploitation signals from CISA KEV, CISA's SSVC data (Vulnrichment), ransomware data, public exploit-code references and EPSS.Tier 2 is not evidence of exploitation. It means a Metasploit module exists, or Exploit-DB marks a public exploit verified, or CISA's SSVC data says "public PoC" and EPSS is 50% or more. EchelonGraph does not test whether exploit code works.Signals for this CVE: an Exploit-DB entry Exploit-DB marks verified, EPSS in the top 5%, EPSS 50% or more.Earliest public exploit code on record: 2004-10-06 (Exploit-DB EDB-24666)EchelonGraph confidence 66%: a heuristic from the tier and the number of signals, not a measured probability.
EchelonGraph scoreMEDIUM confidence
“—” beside the score: it is equal to NVD's CVSS score.
Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-04-29. NVD baseline CVSS 9.8; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
9.8EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
- High exploitation likelihood — EPSS 76%
- Public exploit code is available (Exploit-DB, marked verified by Exploit-DB)
CISA-KEV: Not listedEPSS PROB: 76%CVSS: 9.8Exploit: Exploit-DB (verified)Exposed services: Not assessed
No fix has been recorded since the CVE record was published in 2004 — use a compensating control (WAF / firewall / segmentation) and check the vendor's advisory.
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALmedium confidence
- EG Risk
- 74EG Risk 74/100
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computed (value × EchelonGraph’s weight)Severity98% × 45%The EG Score, 9.8 of 10.Exploitation76% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: No fix has been recorded since the CVE record was published in 2004. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and check the vendor's advisory for a fix. - EPSS PROB
- 76%
- EPSS %ILE
- 99th
- KEV
- Not listed
SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.
No fix has been recorded since the CVE record was published in 2004. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and check the vendor's advisory for a fix.
Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
November 3, 2004
Last Modified
June 16, 2026
Advisory Details (5)
Auto-updated Oct 8, 2026No fix on record since 2004. Sources: cert.
Web page
Microsoft Security Bulletin MS05-004 - Important | Microsoft Learn
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2005/ms05-004CERT
VU#283646 - Microsoft ASP.NET fails to perform proper canonicalization
http://www.kb.cert.org/vuls/id/283646Web page
GUSI / Discussion / Open Discussion
http://sourceforge.net/mailarchive/forum.php?thread_id=5671607&forum_id=24754Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 4× in last 7d / 7× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 14 repeat rows among the latest 68 are merged into the row they repeat.
- 2026-10-12 02:23 UTCEG score recompute
- 2026-10-11 13:37 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-10-09 19:58 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-10-07 23:35 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-10-04 23:15 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-09-29 02:40 UTCEG score recompute
- 2026-09-12 14:54 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-09-10 09:23 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-08-30 01:13 UTCEPSS rescoreEPSS 71% · 99th percentile
- 2026-07-24 14:11 UTCEPSS rescoreEPSS 74% · 99th percentile
- 2026-07-23 00:46 UTCEG score recompute
- 2026-07-23 00:27 UTCEG score recompute
- 2026-07-22 23:50 UTCEG score recompute
- 2026-07-22 21:30 UTCEG score recompute
- 2026-07-20 17:02 UTCEPSS rescoreEPSS 74% · 99th percentile
- 2026-07-19 14:25 UTCEPSS rescoreEPSS 74% · 99th percentile
- 2026-07-13 06:07 UTCEPSS rescoreEPSS 74% · 99th percentile
- 2026-07-04 06:26 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-28 14:02 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-28 04:52 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-27 03:04 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-23 21:29 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-21 01:56 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-17 17:49 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-16 17:49 UTCEPSS rescoreEPSS 76% · 99th percentile
Show 29 moreShow fewer
- 2026-06-15 17:43 UTCEPSS rescoreEPSS 76% · 99th percentile
- 2026-06-12 23:08 UTCEPSS rescoreEPSS 46% · 97th percentile
- 2026-06-11 13:55 UTCEPSS rescoreEPSS 46% · 97th percentile
- 2026-06-10 22:13 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-06-08 14:13 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-06-06 13:44 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-06-05 22:43 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-06-04 13:09 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-06-02 20:10 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-06-01 13:49 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-31 22:28 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-31 00:13 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-29 13:40 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-28 13:42 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-27 13:37 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-26 13:41 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-26 07:16 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-22 21:15 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-20 22:36 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-20 11:20 UTCEPSS rescoreEPSS 53% · 97th percentile
- 2026-05-20 08:30 UTCGHSA enrichmentGHSA-wxfc-g96x-mm56 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-05-20 04:05 UTCGHSA enrichmentGHSA-wxfc-g96x-mm56 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-05-19 23:39 UTCGHSA enrichmentGHSA-wxfc-g96x-mm56 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-05-19 19:14 UTCGHSA enrichmentGHSA-wxfc-g96x-mm56 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-05-19 14:49 UTCGHSA enrichmentGHSA-wxfc-g96x-mm56 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-05-19 06:31 UTCGHSA enrichmentGHSA-wxfc-g96x-mm56 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-05-19 02:05 UTCEG score recompute
- 2026-05-19 02:05 UTCGHSA enrichmentGHSA-wxfc-g96x-mm56 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-05-18 21:29 UTCEPSS rescoreEPSS 53% · 97th percentile
Publicly available exploits
(1 reference)Public exploit code is referenced for this CVE (1 Exploit-DB entry). No fix is on record, so defenders should restrict or isolate affected systems accordingly.
- Exploit-DBEDB-24666✓ verifiedPublished Oct 6, 2004
Microsoft ASP.NET 1.x - URI Canonicalization Unauthorized Web Access
Open source ↗
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2004-0847?
CVE-2004-0847 is a critical-severity vulnerability; its CVE record was published on November 3, 2004. The Microsoft .NET forms authentication capability for ASP.NET allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) "\" (backslash) or (2) "%5C" (encoded backslash), aka "Path Validation Vulnerability."
When was CVE-2004-0847 made public?
CVE-2004-0847 was made public on September 14, 2004: that is the date its CVE record's CNA, MITRE Corporation, gives for when the vulnerability was made public. The CVE record itself was published on November 3, 2004. EchelonGraph's copy of the record carries a last-modified date of June 16, 2026; the record at its source may have been updated since.
Is CVE-2004-0847 actively exploited?
CVE-2004-0847 is not currently on CISA's Known Exploited Vulnerabilities catalog. EchelonGraph's EG-KEV model places it in Tier 2 (Weaponized), which is not evidence of exploitation: Exploit-DB marks a public exploit for it as verified. EchelonGraph does not test whether exploit code works. FIRST EPSS estimates a 76% probability of exploitation in the next 30 days (99th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2004-0847?
CVE-2004-0847 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2004-0847?
No fix for CVE-2004-0847 has been recorded since its CVE record was published in 2004. Restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and check the vendor's advisory for a fix.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2004-0847
Is Your Infrastructure Affected by CVE-2004-0847?
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