CVE-2026-13221: 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 alterna
Noroxi assessment
Priority: Monitor (action score 36/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.49% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: azl3 perl 5.38.2-512 on Azure Linux 3.0 5.38.2-513.
Low priority for now. Upgrade to azl3 perl 5.38.2-512 on Azure Linux 3.0 5.38.2-513 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- EUVD-2026-43503
- ALSA-2026:67155
- ALSA-2026:67156
- ALSA-2026:67162
- ALSA-2026:67278
- openSUSE-SU-2026:21411-1
- RHSA-2026:39997
- RHSA-2026:67155
- RHSA-2026:67156
- RHSA-2026:67162
- RHSA-2026:67278
- RLSA-2026:67155
- RLSA-2026:67156
- RLSA-2026:67162
- RLSA-2026:67278
- SUSE-SU-2026:22847-1
- SUSE-SU-2026:22929-1
- SUSE-SU-2026:23008-1
- SUSE-SU-2026:23075-1
- Published
- Jul 13, 2026
- Updated
- Oct 24, 2026
- EPSS
- 0.4% · 42th percentile
- CWE
- CWE-190
Report tools
Action score
36
Monitor
Low priority for now.
- CVSS
- 36 / 40 · 9.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.1
- CNA · CPANSec
- 9.1
- agree
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| perl | perl | cpe:2.3:a:perl:perl |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- perl perlup to 5.43.9 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (CPANSec). Independent of NVD's CPE analysis and usually ahead of it.
cpan.org/modules perl
- before 5.40.5-RC1affected
- 5.41.0 and later · before 5.42.3-RC1affected
- 5.43.0 and later · before 5.43.10affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | perl | before 4:5.40.2-515.el10_2 | 4:5.40.2-515.el10_2 |
| AlmaLinux:10 | perl-Attribute-Handlers | before 1.03-515.el10_2 | 1.03-515.el10_2 |
| AlmaLinux:10 | perl-AutoLoader | before 5.74-515.el10_2 | 5.74-515.el10_2 |
| AlmaLinux:10 | perl-AutoSplit | before 5.74-515.el10_2 | 5.74-515.el10_2 |
| AlmaLinux:10 | perl-autouse | before 1.11-515.el10_2 | 1.11-515.el10_2 |
| AlmaLinux:10 | perl-B | before 1.89-515.el10_2 | 1.89-515.el10_2 |
| AlmaLinux:10 | perl-base | before 2.27-515.el10_2 | 2.27-515.el10_2 |
| AlmaLinux:10 | perl-Benchmark | before 1.25-515.el10_2 | 1.25-515.el10_2 |
| AlmaLinux:10 | perl-blib | before 1.07-515.el10_2 | 1.07-515.el10_2 |
| AlmaLinux:10 | perl-Class-Struct | before 0.68-515.el10_2 | 0.68-515.el10_2 |
| AlmaLinux:10 | perl-Config-Extensions | before 0.03-515.el10_2 | 0.03-515.el10_2 |
| AlmaLinux:10 | perl-DBM_Filter | before 0.06-515.el10_2 | 0.06-515.el10_2 |
| AlmaLinux:10 | perl-debugger | before 1.60-515.el10_2 | 1.60-515.el10_2 |
| AlmaLinux:10 | perl-deprecate | before 0.04-515.el10_2 | 0.04-515.el10_2 |
| AlmaLinux:10 | perl-devel | before 4:5.40.2-515.el10_2 | 4:5.40.2-515.el10_2 |
| AlmaLinux:10 | perl-Devel-Peek | before 1.34-515.el10_2 | 1.34-515.el10_2 |
| AlmaLinux:10 | perl-Devel-SelfStubber | before 1.06-515.el10_2 | 1.06-515.el10_2 |
| AlmaLinux:10 | perl-diagnostics | before 1.40-515.el10_2 | 1.40-515.el10_2 |
| AlmaLinux:10 | perl-DirHandle | before 1.05-515.el10_2 | 1.05-515.el10_2 |
| AlmaLinux:10 | perl-doc | before 5.40.2-515.el10_2 | 5.40.2-515.el10_2 |
| AlmaLinux:10 | perl-Dumpvalue | before 2.27-515.el10_2 | 2.27-515.el10_2 |
| AlmaLinux:10 | perl-DynaLoader | before 1.56-515.el10_2 | 1.56-515.el10_2 |
| AlmaLinux:10 | perl-encoding-warnings | before 0.14-515.el10_2 | 0.14-515.el10_2 |
| AlmaLinux:10 | perl-English | before 1.11-515.el10_2 | 1.11-515.el10_2 |
+96
Same product
perl: all recordsOther highest-scoring records for the same primary product.
- CVE-2012-6329The _compile function in Maketext.pm in the Locale::Maketext implementation in Perl before 5.17.7 does not properly handle backslashes and f49Plan
- CVE-2018-18311Perl before 5.26.3 and 5.28.x before 5.28.1 has a buffer overflow via a crafted regular expression that triggers invalid write operations.43Plan
- CVE-2018-18312Perl before 5.26.3 and 5.28.0 before 5.28.1 has a buffer overflow via a crafted regular expression that triggers invalid write operations.43Plan
Published before and after this one in the same product
- ← EarlierCVE-2026-4176Mar 29, 2026 · Perl versions from 5.9.4 before 5.40.4-RC1, from 5.41.0 before 5.42.2-RC1, from 5.43.0 before 5.43.9 contain a vulnerable version of Compress::Raw::Zlib39Monitor
- ← EarlierCVE-2026-8376May 25, 2026 · Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have a heap buffer overflow when compiling regular expressions with a39Monitor
- Later →CVE-2026-57432Jul 13, 2026 · Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have an integer overflow in S_measure_struct leading to an out-of-bou33Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| azl3 perl 5.38.2-512 on Azure Linux 3.0 | 5.38.2-513 · CBL-Mariner Releases | Microsoft (MSRC) |
| almalinux:perl | 4:5.32.1-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-Attribute-Handlers | 1.01-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-AutoLoader | 5.74-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-AutoSplit | 5.74-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-B | 1.80-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-Benchmark | 1.23-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-Class-Struct | 0.66-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-Config-Extensions | 0.03-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-DBM_Filter | 0.06-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-Devel-Peek | 1.28-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-Devel-SelfStubber | 1.06-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:perl-DirHandle | 1.05-484.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| alpine:perl | 5.42.2-r1 · Alpine:v3.24 | Package registry (OSV) |
| debian:perl | 5.36.0-7+deb12u4 · Debian:12 | Package registry (OSV) |
| debian:perl | 5.40.1-6+deb13u1 · Debian:13 | Package registry (OSV) |
| opensuse:perl | 5.42.0-160000.3.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| red hat:perl | 0:5.42.2-524.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:perl-Attribute-Handlers | 0:1.03-524.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:perl-AutoLoader | 0:5.74-484.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:perl-AutoLoader | 0:5.74-524.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:perl-AutoSplit | 0:5.74-484.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:perl-AutoSplit | 0:5.74-524.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:perl-B | 0:1.80-484.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:perl-B | 0:1.89-524.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:perl-B-debuginfo | 0:1.80-484.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:perl-Benchmark | 0:1.23-484.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:perl-Benchmark | 0:1.27-524.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:perl-Class-Struct | 0:0.66-484.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:perl-Class-Struct | 0:0.68-524.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
+22
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-190 · Integer Overflow or WraparoundCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.