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Fencer Vulns
medium 6.3

CVE-2026-82729 json

Quadratic chunk-size parsing in Mint.HTTP1.Parse allows CPU-exhaustion DoS

published 2026-09-04 2 mo ago modified 2026-09-08 2 mo ago also EEF-CVE-2026-82729 , GHSA-7p8w-j234-7qc8 , EUVD-2026-71219

cvss
6.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

Inefficient Algorithmic Complexity vulnerability in elixir-mint mint allows a remote HTTP server to exhaust CPU on the client host and cause a denial of service.

parse_hex_prefix/2 in lib/mint/http1/parse.ex folds each hex digit of a chunked response's chunk-size field into an arbitrary-precision accumulator with acc * 16 + digit and imposes no limit on the digit count. Because the accumulator grows without bound, the multiplication is not constant time and one pass over N digits costs O(N squared). handle_data/2 prepends conn.buffer and re-parses from the start on every socket message, so a server that dribbles the digits out in small packets makes the client pay that cost repeatedly. A run of roughly 512,000 hex digits costs over ten seconds of CPU in a single pass, measured on stock defaults. The parser reaches this state after a valid status line and a complete, valid header section, so an intermediary inspecting only headers sees an ordinary 200 response.

This issue affects mint: from 1.9.3 before 1.10.0.

Patch / fix

  • hex mint 1.10.0
  • elixir-mint mint 1.10.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/elixir-mint/mint/security/advisories/GHSA-7p8w-j234-7qc8 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
hex mint
>=1.9.3, <1.10.0
1.10.0

Affected products

  • elixir-mint mint

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

References

Sources

Fencer Vulns 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.