CVE-2023-5722Network attack vector

Cross-origin metadata disclosure via Cache API oracle

Published Oct 24, 2023 · Updated Feb 13, 2025

Information disclosure in Mozilla Firefox before 119 allows remote attackers to infer cross-origin response sizes and Vary header contents. The Cache API exposes accept-or-reject differences while processing opaque no-cors range requests and Vary matching, creating an oracle for iterative size probing and header-value guessing. A malicious site must induce repeated cross-origin browser requests; the reported consequence is limited to response metadata and user-state disclosure.

CVSS severity5.3
Medium
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Mozilla Firefox before 119 allows remote attackers to infer cross-origin response sizes and Vary header contents. The Cache API exposes accept-or-reject differences while processing opaque no-cors range requests and Vary matching, creating an oracle for iterative size probing and header-value guessing. A malicious site must induce repeated cross-origin browser requests; the reported consequence is limited to response metadata and user-state disclosure.

The record

CVE
CVE-2023-5722
Published
Oct 24, 2023
Updated
Feb 13, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=unspecified <119

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <119

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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