How severe is CVE-2026-31835?

CVE-2026-31835 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.

Is CVE-2026-31835 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-31835?

CVE-2026-31835 affects Dani-garcia Vaultwarden. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-31835?

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

Does CVE-2026-31835 have an EU (EUVD) identifier?

Yes. CVE-2026-31835 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27424.

When was CVE-2026-31835 published?

CVE-2026-31835 was published on 2026-05-05 and last updated on 2026-06-17.

CVE-2026-31835

CVE-2026-31835 is a medium-severity vulnerability in Dani-garcia Vaultwarden with a CVSS 3.x base score of 5.4. 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-345.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v4: 5.3
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27424
Weakness: CWE-345
Affected product: Dani-garcia Vaultwarden
Published: 2026-05-05
Last modified: 2026-06-17

Description

Vaultwarden is a Bitwarden-compatible server written in Rust. In versions 1.35.4 and earlier, the WebAuthn authentication flow in `validate_webauthn_login()` updates persistent credential metadata (1backup_eligible1 and 1backup_state flags1) based on unverified `authenticatorData` before signature validation is performed. An attacker who knows a user's password but cannot produce a valid WebAuthn signature can permanently modify the stored backup flags for that user's credential. If signature verification fails, the database update is not rolled back. This can result in a persistent denial of service of WebAuthn two-factor authentication for affected credentials. This issue has been fixed in version 1.35.5.

Frequently asked questions

What is CVE-2026-31835?: Vaultwarden is a Bitwarden-compatible server written in Rust. In versions 1.35.4 and earlier, the WebAuthn authentication flow in `validate_webauthn_login()` updates persistent credential metadata (1backup_eligible1 and 1backup_state flags1) based on unverified `authenticatorData` before signature validation is performed. An attacker who knows a user's password but cannot produce a valid WebAuthn signature can permanently modify the stored backup flags for that user's credential. If signature verification fails, the database update is not rolled back. This can result in a persistent denial of service of WebAuthn two-factor authentication for affected credentials. This issue has been fixed in version 1.35.5.
How severe is CVE-2026-31835?: CVE-2026-31835 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.
Is CVE-2026-31835 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-31835?: CVE-2026-31835 affects Dani-garcia Vaultwarden. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-31835?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-31835 have an EU (EUVD) identifier?: Yes. CVE-2026-31835 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27424.
When was CVE-2026-31835 published?: CVE-2026-31835 was published on 2026-05-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:dani-garcia:vaultwarden:*:*:*:*:*:*:*:*

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