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Fencer Intel
high 7.5

CVE-2026-77299 json

Regexp2: Unbounded memory amplification via large `{m}` quantifier on a zero-width subexpression

published 4mo ago modified 5d ago also EUVD-2026-117884 , GHSA-wq9v-j77v-qr26

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository dlclark/regexp2. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits
0
none known

Summary

Regexp2 is a feature-rich RegExp engine for Go. Prior to version 2.3.0, when regexp2 compiles and matches a pattern containing a large fixed-count quantifier applied to a zero-width subexpression — e.g. (?:){50000000} — the match engine executes the empty loop body m-1 times, pushing two integers onto the backtracking stack on every iteration. Because the parser accepts any repetition count up to math.MaxInt32 and the backtracking stack grows without bound, a pattern of fewer than 20 bytes matched against an empty input can force multi-gigabyte allocation and OOM-kill the process. MatchTimeout does not fully mitigate this because the memory is allocated faster than the 100 ms timeout clock can fire. This issue has been patched in version 2.3.0.

Patch / fix

Is CVE-2026-77299 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-77299 updated cvss 7.5

github.com/dlclark/regexp2: regexp2: Denial of Service via unbounded memory allocation during pattern matching

  • Red Hat Ceph Storage 8 rhceph/rhceph-promtail-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images hugo 0.169.0-0.1.hum1, trivy 0.76.1-0.2.hum1 Red Hat Openshift Data Foundation 4 odf4/odf-multicluster-rhel9-operator
    affected: workaround, no fix available
  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/logging-loki-rhel9 Red Hat Migration Toolkit for Applications 8 mta/mta-cli-rhel9, mta/mta-analyzer-addon-rhel9, mta/mta-solution-server-rhel9, mta/mta-go-external-provider-rhel9, mta/mta-java-external-provider-rhel9, mta/mta-nodejs-external-provider-rhel9, +1 more Red Hat Multicluster Global Hub multicluster-globalhub/multicluster-globalhub-grafana-rhel9 Red Hat Multicluster Global Hub 5 multicluster-globalhub/multicluster-globalhub-grafana-rhel9 Red Hat OpenShift Service Mesh 3 istio-proxy-selinux, istio-proxy 1.30.5-1.el9, openshift-service-mesh/istio-cni-rhel9, openshift-service-mesh/istio-pilot-rhel9, openshift-service-mesh/istio-proxyv2-rhel9 Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/acm-grafana-rhel9, rhacm2/kube-state-metrics-rhel9
    +7 more products
    Red Hat Enterprise Linux 8 grafana, grafana-loki, grafana-mssql, grafana-mysql, grafana-selinux, grafana-graphite, +9 more Red Hat Enterprise Linux 9 grafana, grafana-selinux, gvisor-tap-vsock, grafana 12.4.3-2.el10, gvisor-tap-vsock-gvforwarder, gvisor-tap-vsock 0.8.7-3.el10 Red Hat Enterprise Linux 10 grafana 12.4.3-2.el10, gvisor-tap-vsock 0.8.7-3.el10 Red Hat OpenShift Container Platform 4 openshift, microshift, microshift-olm, microshift-sriov, microshift-multus, openshift-clients, +35 more Red Hat OpenShift Container Platform 5 openshift5/ose-etcd-rhel9, openshift5/ose-dpu-cni-rhel9, openshift5/ose-dpu-daemon-rhel9, openshift5/ose-dpu-rhel9-operator, openshift5/ose-dpu-marvell-vsp-rhel9, openshift5/ose-kube-state-metrics-rhel9, +8 more Red Hat OpenShift GitOps openshift-gitops-1/argocd-rhel9, openshift-gitops-1/gitops-rhel9, openshift-gitops-1/argocd-agent-rhel9, openshift-gitops-1/gitops-rhel9-operator, openshift-gitops-1/argocd-image-updater-rhel9 Red Hat OpenStack Platform 18.0 rhoso-operators/openstack-operator-bundle
    under investigation
  • Red Hat Hardened Images etcd 3.7.3-0.1.hum1, loki3.7 3.7.9-0.2.hum1, loki3.6 3.6.19-0.2.hum1, tempo3.0 3.0.4-0.3.hum1, tempo2.10 2.10.9-0.1.hum1, grafana13.1 13.1.8-0.6.hum1, +4 more
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5d ago

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/dlclark/regexp2/security/advisories/GHSA-wq9v-j77v-qr26 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • dlclark regexp2

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of dlclark/regexp2 published their own advisory on GitHub. Reviewed sources take precedence over it.