CVE-2026-48840
Exim 4.88 – 4.99.4
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-48840 is a medium-severity Numeric Range Comparison Without Minimum Check (CWE-839) vulnerability in Exim Exim. Its CVSS base score is 5.3 (Medium).
Operationally, ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-33446
Vulnerability Data
Exim 4.88 before 4.99.4, in some proxy configurations, mishandles certain short payloads, leading to disclosure of uninitialized stack memory values to a client.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 2 hardening rules · 1 OS baseline
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Mitigating Controls (NIST 800-53 r5) AI
SI-10 requires validity checks on information inputs, directly stopping missing lower-bound range verification from being introduced.
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.
Secure SDLC practices directly require proper input validation and range checks that prevent missing minimum bounds.
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.
Security testing in development and acceptance can detect missing minimum checks through boundary-value and fuzz testing.
Secure development life cycle mandates input validation and boundary checks that would catch missing minimum-range verification.
Application security requirements include explicit validation rules for numeric ranges, directly addressing the missing minimum check.
Secure system architecture principles require defensive input handling and range validation to prevent out-of-bounds values.
Secure coding standards explicitly forbid numeric comparisons that omit the lower bound, directly mitigating CWE-839.