# CVE-2026-121006: HTTP::Body Perl trailer parsing quadratic time complexity denial of service

Source: https://junglewise.ai/threats/cve-2026-121006-http-body-versions-before-1-24-02-for-perl-parse-the-trailer-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-06. Updated: 2026-11-06  
License: CC BY 4.0 with a link back

CVE-2026-121006 · Severity: info · Published 2026-11-06

HTTP::Body is a Perl library that parses HTTP request and response bodies. A flaw in how it processes HTTP chunked transfer encoding trailers allows a remote attacker to exhaust server CPU with a single malicious request containing many duplicate header field names. This causes a denial of service that impacts any web service or application using HTTP::Body for request parsing.

Technologies: [Perl HTTP::Body](https://junglewise.ai/threats/technologies/http-body). Vendors: [Perl](https://junglewise.ai/threats/vendors/perl).

## Quick answers

**Is CVE-2026-121006 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121006 being exploited in the wild.

**How severe is CVE-2026-121006?** Informational severity, published 6 November 2026.

**Which products and versions are affected?** Perl HTTP::Body before 1.24_02.

**Is there a fix for CVE-2026-121006?** Yes: fixed in HTTP::Body 1.24_02. Until then: Upgrade to HTTP::Body version 1.24_02 or later. The fix enforces limits on trailer size (32,768 bytes) and the number of header lines (100) in chunked bodies to prevent quadratic-time parsing. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-121006 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-121006?** Check whether you run Perl HTTP::Body at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in HTTP::Body 1.24_02

Upgrade to HTTP::Body version 1.24_02 or later. The fix enforces limits on trailer size (32,768 bytes) and the number of header lines (100) in chunked bodies to prevent quadratic-time parsing.

## Technical details

HTTP::Body before version 1.24_02 parses chunked transfer encoding trailers using HTTP::Headers, which has quadratic time complexity when processing multiple headers with the same field name. An attacker can send a single HTTP request with a chunked body whose trailer contains thousands of duplicate header lines (e.g., 16 KiB of "a:" lines), causing the parser to consume several seconds of CPU time per request. Version 1.24_02 and later limit trailer size to 32,768 bytes and 100 header lines to mitigate this attack.

## Affected products

- Perl HTTP::Body before 1.24_02

## Timeline

- 2026-11-06: disclosed
- 2026-11-03: patched

## References

- [https://cpan.org/modules](https://cpan.org/modules)
- [https://github.com/libwww-perl/HTTP-Body/commit/983dd4ca3b863ab513240b02c91c3114fb299389.patch](https://github.com/libwww-perl/HTTP-Body/commit/983dd4ca3b863ab513240b02c91c3114fb299389.patch)

## Related threats

- [HTTP::Body unbounded memory buffering in chunked request parsing](https://junglewise.ai/threats/cve-2026-117501-http-body-versions-before-1-24-01-for-perl-allow-memory)
- [HTTP::Body regex backtracking DoS in multipart filename parsing](https://junglewise.ai/threats/cve-2026-117500-http-body-versions-before-1-24-01-for-perl-allow-cpu-exhaustion)