Cyber Resilience

CVE-2023-5388

Mozilla Firefox ≤ 115.9.0

Published
19 March 2024
Modified
04 November 2025
Patch / advisory
View advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
EPSS Score 0.0082 54th percentile
Risk Priority 52 floored blend · peak EPSS

Summary

CVE-2023-5388 is a medium-severity Observable Discrepancy (CWE-203) vulnerability in Mozilla Firefox. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Account Discovery (T1087); ranked in the top 46% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to IA-6 (Authentication Feedback) and SI-11 (Error Handling) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

NSS was susceptible to a timing side-channel attack when performing RSA decryption. This attack could potentially allow an attacker to recover the private data. This vulnerability affects Firefox < 124, Firefox ESR < 115.9, and Thunderbird < 115.9.

CWE(s)
CWE-203

Related Threats

MITRE ATT&CK Enterprise Techniques

T1087 Account Discovery Discovery
Adversaries may attempt to get a listing of valid accounts, usernames, or email addresses on a system or within a compromised environment.
attack.mitre.org →
T1110 Brute Force Credential Access
Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.
attack.mitre.org →
T1595 Active Scanning Reconnaissance
Adversaries may execute active reconnaissance scans to gather information that can be used during targeting.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-5690Same product: Debian Debian Linux
CVE-2024-10463Same product: Mozilla Firefox
CVE-2024-9398Same product: Mozilla Firefox
CVE-2023-25728Same product: Mozilla Firefox
CVE-2024-4767Same product: Debian Debian Linux
CVE-2024-3861Same product: Debian Debian Linux
CVE-2024-2614Same product: Debian Debian Linux
CVE-2024-1548Same product: Debian Debian Linux
CVE-2024-2611Same product: Debian Debian Linux
CVE-2024-2607Same product: Debian Debian Linux

Affected Assets

mozilla
firefox
≤ 115.9.0 · ≤ 124.0
mozilla
thunderbird
≤ 115.9.0
debian
debian linux
10.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 1 hardening rule · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

IA-6 Authentication Feedback good match

Obscures authentication feedback so that success/failure differences are not observable to attackers.

SI-11 Error Handling good match

Requires error messages to avoid revealing exploitable details, directly stopping observable response discrepancies.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent observable response discrepancies via consistent error handling and timing.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.17 Clock synchronization none match
none

Accurate, synchronized timestamps reduce observable timing discrepancies that an attacker could exploit to infer sensitive information or distinguish between success and failure paths.

References