How severe is CVE-2026-43861?

CVE-2026-43861 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-43861 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-43861?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-43861 have an EU (EUVD) identifier?

Yes. CVE-2026-43861 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26899.

When was CVE-2026-43861 published?

CVE-2026-43861 was published on 2026-05-04 and last updated on 2026-06-17.

CVE-2026-43861

CVE-2026-43861 is a low-severity vulnerability with a CVSS 3.x base score of 3.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-158.

Key facts

Severity: Low (CVSS 3.x base score 3.7)
EPSS exploit prediction: 0% (6th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-26899
Weakness: CWE-158
Published: 2026-05-04
Last modified: 2026-06-17

Description

mutt before 2.3.2 does not check for '\0' in url_pct_decode.

Frequently asked questions

What is CVE-2026-43861?: mutt before 2.3.2 does not check for '\0' in url_pct_decode.
How severe is CVE-2026-43861?: CVE-2026-43861 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-43861 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-43861?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-43861 have an EU (EUVD) identifier?: Yes. CVE-2026-43861 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26899.
When was CVE-2026-43861 published?: CVE-2026-43861 was published on 2026-05-04 and last updated on 2026-06-17.

References

https://github.com/muttmua/mutt/commit/12f54fe3b61f761c096fe95e95d5e3072af00ed2

Other CWE-158 vulnerabilities

CVE-2025-47812 — Critical (CVSS 10.0): In Wing FTP Server before 7.4.4. the user and admin web interfaces mishandle '\0' bytes, ultimately allowing injection…
CVE-2025-14388 — Critical (CVSS 9.8): The PhastPress plugin for WordPress is vulnerable to Unauthenticated Arbitrary File Read via null byte injection in all…
CVE-2025-55113 — Critical (CVSS 9.0): If the Access Control List is enforced by the Control-M/Agent and the C router is in use (default in Out-of-support…
CVE-2023-5719 — High (CVSS 8.8): The Crimson 3.2 Windows-based configuration tool allows users with administrative access to define new passwords for…
CVE-2009-1537 — High (CVSS 8.8): Unspecified vulnerability in the QuickTime Movie Parser Filter in quartz.dll in DirectShow in Microsoft DirectX 7.0…
CVE-2025-9648 — High (CVSS 8.7): A vulnerability in the CivetWeb library's function mg_handle_form_request allows remote attackers to trigger a denial…

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