CVE-2026-4926
path-to-regexp vulnerable to Denial of Service via sequential optional groups
No known exploitation. EPSS puts it in the 58th percentile. No fix published yet.
What to do
No fixed build or workaround is published yet. Limit exposure and watch for a patch.
What it is
From the CVE record
Impact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service. Patches: Fixed in version 8.4.0. Workarounds: Limit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.9% chance of exploitation activity in the next 30 days, which ranks it in the 58th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
19 events over 167 days, from the signal feeds we watch.
- Record updated
- Record updated
- Record updated
- Record updated
- Record updated
- Record updated
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Scored 7.5 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality NoneNo confidentiality impact
- Integrity NoneNo integrity impact
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
References in the record
- cna.openjsf.org/security-advisories.html
- access.redhat.com/errata/RHSA-2026:10153
- access.redhat.com/errata/RHSA-2026:10172
And 19 more references. See all after sign-in
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