CVE-2026-13221
No exploitation reported by the sources we read.
- Published2026-07-13
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
Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.10 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk. When such branches are combined into a trie, the delta between the first branch and the shared tail is stored in a 16-bit field. A branch count above 65535 overflows the field, and the trie's match decision table is truncated with no warning or error. A pattern of this shape produces false positive matches (matching strings it should not) and false negative matches (failing to match strings it should). When such a pattern gates an access or filtering decision, the result is wrong.
Timeline
dates in UTC- 2026-07-1317:16CVE publishedNVD
Versions per branch
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.
Packages
- perlAlmaLinux:10all versions · fixed in 4:5.40.2-515.el10_2and 5 other packages
- perlAlmaLinux:9all versions · fixed in 4:5.32.1-484.el9_8and 5 other packages
- perlAlmaLinux:8all versions · fixed in 4:5.32.1-475.module_el8.10.0+4278+b5f6cf5fand 5 other packages
- perl-Algorithm-DiffAlmaLinux:8all versions · fixed in 1.1903-10.module_el8.6.0+2766+8bf0b7ce
- perl-Archive-TarAlmaLinux:8all versions · fixed in 2.38-5.module_el8.10.0+4240+a58b978c
- perl-Archive-ZipAlmaLinux:8all versions · fixed in 1.68-3.module_el8.6.0+2766+8bf0b7ce
- perl-Attribute-HandlersAlmaLinux:9all versions · fixed in 1.01-484.el9_8
- perl-Attribute-HandlersAlmaLinux:8all versions · fixed in 1.01-475.module_el8.10.0+4278+b5f6cf5f
308 more package ranges on OSV.dev
Vendor advisories
perl: Perl: Incorrect regular expression processing via large regular expressions
perl as a component of Red Hat Enterprise Linux 6 · perl-Archive-Extract as a component of Red Hat Enterprise Linux 6 · perl-Archive-Tar as a component of Red Hat Enterprise Linux 6 · +66 more
Red Hat Security Advisory: Red Hat Cost Management On-Premise container image update
Red Hat Security Advisory: OpenShift Container Platform 4.22.16 bug fix and security update
Red Hat Security Advisory: Red Hat Update Infrastructure 5.3 security update
Red Hat Security Advisory: perl:5.32 security update
Red Hat Security Advisory: perl security update
3 more advisories
Fix
- Vendor fix Red Hat Product Security RHSA-2026:79357 · 1 productThe container image provided by this update can be downloaded from the Red Hat container registry at registry.redhat.io using the "podman pull" command.
- Vendor fix Red Hat Product Security RHSA-2026:71446 · 4 productsFor OpenShift Container Platform 4.22 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
- Vendor fix Red Hat Product Security RHSA-2026:67956 · 1 productThe container images provided by this release, apart from the installer, should be deployed using rhui-installer utility. See the official documentation for more details.
- Vendor fix Red Hat Product Security RHSA-2026:67278 · 794 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
- Vendor fix Red Hat Product Security RHSA-2026:39997 · 203 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
- No fix available, says the vendor Red Hat Product Security CVE-2026-13221 · 69 productsAffected
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
- NVDCVE recordread 2026-07-15
- FIRST EPSSEPSS score0.4 %2026-10-22
- OSVaffected packages—
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- Published
- 2026-07-13
- Last Modified
- 2026-07-14
Frequently asked questions
What is CVE-2026-13221?
Is CVE-2026-13221 actively exploited?
What is the CVSS score for CVE-2026-13221?
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