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CVE-2026-115866

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies

7.5 HighFix available

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.38%Up 0.1 points since Oct 31, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.5

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Record
CVE-2026-115866
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-1333
Updated
2026-11-06
EUVDEUVD-2026-113907 7.5

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Record
EUVD-2026-113907
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-06
GitHub AdvisoriesGHSA-8jc4-2m4j-6vf8 7.5

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression...

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Record
GHSA-8jc4-2m4j-6vf8
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-1333
Updated
2026-11-06
NVD 7.5

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Record
CVE-2026-115866
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-1333
Updated
2026-11-06
OSV 7.5

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Record
CVE-2026-115866
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-1333
Updated
2026-11-07
OSVDEBIAN-CVE-2026-115866 7.5

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies. A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads. A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Record
DEBIAN-CVE-2026-115866
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-07
OSVUBUNTU-CVE-2026-115866 No score

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies. A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads. A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Record
UBUNTU-CVE-2026-115866
Updated
2026-11-05

Affected packages

Affected packages
PackageAffectedFixed
starlet
Debian:12
All versions, plus listed versions
0.31-20.31-30.32-10.33-1
None known
starlet
Debian:13
All versions, plus listed versions
0.31-20.31-2+deb13u10.31-30.32-10.33-1
None known
starlet
Debian:14
before 0.33-1, plus listed versions
0.31-20.31-30.32-1
0.33-1
starlet
Ubuntu:16.04:LTS
All versions, plus listed versions
0.25-10.26-10.28-1
None known
starlet
Ubuntu:18.04:LTS
All versions, plus listed versions
0.31-1
None known
starlet
Ubuntu:20.04:LTS
All versions, plus listed versions
0.31-1
None known
starlet
Ubuntu:22.04:LTS
All versions, plus listed versions
0.31-1.1
None known
starlet
Ubuntu:24.04:LTS
All versions, plus listed versions
0.31-2
None known
starlet
Ubuntu:26.10
All versions, plus listed versions
0.31-2build10.31-30.32-1
None known
starlet
Ubuntu:26.04:LTS
All versions, plus listed versions
0.31-20.31-2build1
None known

History

History
RecordedChangedSources
severityCVE List, OSV
affected, aliases, facts, referencesOSV
affected, factsOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-115866 is a high vulnerability (CVSS 7.5) in starlet, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.38%, the 32nd percentile. Fixed in starlet 0.33-1.

References

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