CVE-2026-33691

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 3.6%, top 12% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 4%CVSS: 7.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.9 and 4.25.0, a bypass was identified in OWASP CRS that allows uploading files with dangerous extensions (.php, .phar, .jsp, .jspx) by inserting whitespace padding in the filename (e.g. photo. php or shell.jsp ). The affected rules do not normalize whitespace before evaluating the file extension regex, so the dot-extension check fails to match. This issue has been patched in versions 3.3.9 and 4.25.0.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: Track

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
Severity75% × 45%
Exploitation4% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
4%
EPSS %ILE
88%
KEV
Not listed

Published

April 2, 2026

Last Modified

July 24, 2026

Advisory Details (10)

Auto-updated Jul 24, 2026
Patch available. Sources: github, github_commit, github_pr, github_release.
generic

oss-security - Re: [CVE-2026-33691] OWASP CRS whitespace padding bypass vulnerability

http://www.openwall.com/lists/oss-security/2026/04/18/4
generic

oss-security - [CVE-2026-33691] OWASP CRS whitespace padding bypass vulnerability

http://www.openwall.com/lists/oss-security/2026/03/29/2
generic

Full Disclosure: [CVE-2026-33691] OWASP CRS whitespace padding bypass vulnerability

http://seclists.org/fulldisclosure/2026/Apr/0
github Patch Available

Whitespace padding in filenames bypasses file upload extension checks · Advisory · coreruleset/coreruleset · GitHub

https://github.com/coreruleset/coreruleset/security/advisories/GHSA-rw5f-9w43-gv2w
github_release Patch Available

v4.25.0 (LTS)

Patch available: coreruleset/coreruleset v4.25.0

https://github.com/coreruleset/coreruleset/releases/tag/v4.25.0
github_release Patch Available

v3.3.9

Patch available: coreruleset/coreruleset v3.3.9

https://github.com/coreruleset/coreruleset/releases/tag/v3.3.9
github_pr

fix(944140): prevent whitespace padding bypass in JSP file upload detection

Fix merged in coreruleset/coreruleset PR #4548 on 2026-03-15 — awaiting tagged release

https://github.com/coreruleset/coreruleset/pull/4548
github_pr

fix(933111): prevent whitespace padding bypass in PHP double-extension upload

Fix merged in coreruleset/coreruleset PR #4547 on 2026-03-15 — awaiting tagged release

https://github.com/coreruleset/coreruleset/pull/4547
github_pr

fix(933110): prevent whitespace padding bypass in PHP upload detection

Fix merged in coreruleset/coreruleset PR #4546 on 2026-03-15 — awaiting tagged release

https://github.com/coreruleset/coreruleset/pull/4546
github_commit

commit 2a8c63512811 (coreruleset/coreruleset)

Fix landed in coreruleset/coreruleset commit 2a8c63512811 — awaiting tagged release

https://github.com/coreruleset/coreruleset/commit/2a8c63512811c5dd74472becebb79a783e68ff02

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 15× in last 7d / 42× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 105 total refreshes for this CVE.

  1. 2026-07-27 14:13 UTCEPSS rescore
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-26 14:54 UTCEPSS rescore
  4. 2026-07-26 09:29 UTCEG score recompute▲ 0.70
  5. 2026-07-25 14:18 UTCEPSS rescore
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  7. 2026-07-24 22:11 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
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Frequently asked(5)

What is CVE-2026-33691?
CVE-2026-33691 is a high vulnerability published on April 2, 2026. The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.9 and 4.25.0, a bypass was identified in OWASP CRS that allows uploading files with dangerous extensions (.php, .phar, .jsp, .jspx) by inserting…
When was CVE-2026-33691 disclosed?
CVE-2026-33691 was first published in the National Vulnerability Database on April 2, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33691 actively exploited?
CVE-2026-33691 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4% probability of exploitation in the next 30 days, which ranks it in the top 11.8% of all scored CVEs.
What is the CVSS score of CVE-2026-33691?
CVE-2026-33691 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-33691?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33691, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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