CVE-2026-4926
No exploitation reported by the sources we read.
- Published2026-03-26
- Fixed in8.4.0
- WeaknessCWE-1333 · CWE-400
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
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.
Timeline
dates in UTC- 2026-03-2619:17CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-4926?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-4926?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 8.x | ≥ 8.0.0, < 8.4.0 | 8.4.0 | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
Red Hat Security Advisory: Red Hat Ansible Automation Platform 2.6 Container Release Update
Red Hat Security Advisory: Red Hat Ansible Automation Platform 2.5 Product Security and Bug Fix Update
Red Hat Security Advisory: Red Hat Ansible Automation Platform 2.6 Product Security and Bug Fix Update
Red Hat Security Advisory: Red Hat build of Cryostat 4.2.0: new RHEL 9 container image security update
Red Hat Security Advisory: Red Hat Developer Hub 1.9.4 release.
Red Hat Security Advisory: Red Hat Ansible Automation Platform 2.6 Container Release Update
2 more advisories
Fix
- Update Pillarjs path-to-regexp to 8.4.0
- Vendor fix Red Hat Product Security RHSA-2026:24866 · 4 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://docs.redhat.com/en/documentation/red_hat_ansible_automation_platform/2.6#Upgrade
- Vendor fix Red Hat Product Security RHSA-2026:24761 · 2 productsFor details on how to apply this update, refer to Ansible Automation Platform documentation.
- Vendor fix Red Hat Product Security RHSA-2026:17789 · 2 productsYou can download the Cryostat 4 on RHEL 9 container images that this update provides from the Red Hat Container Registry at registry.access.redhat.com. Installation instructions for your platform are available in the Red Hat Container Catalog (see the References section). Dockerfiles and scripts s…
- Vendor fix Red Hat Product Security RHSA-2026:13826 · 1 productFor more about Red Hat Developer Hub, see References links
- Vendor fix Red Hat Product Security RHSA-2026:10175 · 8 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
- Workaround from the vendor Red Hat Product Security RHSA-2026:24866 · 114 productsTo mitigate this vulnerability, limit the use of multiple sequential optional groups in route patterns within applications that use `path-to-regexp`. Additionally, avoid directly passing user-controlled input as route patterns to prevent the generation of maliciously crafted regular expressions.
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2026-03-26
- Last Modified
- 2026-09-09
- NVD status
- Modified
Frequently asked questions
What is CVE-2026-4926?
Is CVE-2026-4926 actively exploited?
What is the CVSS score for CVE-2026-4926?
Running Red Hat Ansible Automation? Hear about its next vulnerability
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
No credit card required · No monthly cap on website lookups · 250 API requests/month
Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
- Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.
Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.