CVE-2026-93750Public exploitNetwork attack vector

Cross-client response disclosure via Vary wildcard miscomparison

Published Sep 18, 2026 · Updated Sep 18, 2026

Cache validation failure in http-cache-semantics 4.2.0 and earlier allows remote attackers to read other clients' cached responses. The _varyMatches() function compares Vary against a byte-exact wildcard, then treats trimmed or prototype-derived field values as matching. Exploitation requires a shared cache and origin-reachable noncanonical Vary formatting; the reported consequence is cross-client response disclosure.

CVSS severity8.2
High
EPSS probability0.45%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cache validation failure in http-cache-semantics 4.2.0 and earlier allows remote attackers to read other clients' cached responses. The _varyMatches() function compares Vary against a byte-exact wildcard, then treats trimmed or prototype-derived field values as matching. Exploitation requires a shared cache and origin-reachable noncanonical Vary formatting; the reported consequence is cross-client response disclosure.

The record

CVE
CVE-2026-93750
Published
Sep 18, 2026
Updated
Sep 18, 2026
Vendor
Kornel Lesiński
Product
http-cache-semantics
Classifications
CWE-436
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=4.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kornel Lesiński · http-cache-semanticsversion=0 <=4.2.0

Published CVSS scores

8.2VulnCheckCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
5.9VulnCheckCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-436Interpretation Conflict

Public exploit references

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Technologies

Your stack

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Your stack

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