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Fencer Vulns
high 8.7

CVE-2026-105659 json

HTTP/2 blocked-send deadlines reset on every WINDOW_UPDATE, letting a trickle pin stream processes indefinitely in Bandit

published 2026-10-14 25 d ago modified 2026-10-16 23 d ago also EEF-CVE-2026-105659 , GHSA-69m6-wcv4-rwcf , EUVD-2026-101380

cvss
8.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

Uncontrolled Resource Consumption vulnerability in mtrudel bandit allows an unauthenticated remote attacker to pin HTTP/2 stream processes indefinitely via a trickle of small WINDOW_UPDATE frames. A stream whose response outruns the connection or stream send window blocks until the peer grants more window, and each block carries a 15 second deadline. Both deadlines restart whenever the peer makes partial progress. Bandit.HTTP2.Connection.finish_data/5 re-queues a partially advanced send in pending_sends with a fresh expires_at, so every WINDOW_UPDATE on stream 0, and every SETTINGS frame, resets the clock. Bandit.HTTP2.Stream.send_data/3 recurses on each stream WINDOW_UPDATE and re-arms a fresh after read_timeout. A peer that grants a few bytes every few seconds keeps the blocked stream process, its Plug state and any resource it holds mid-response alive for as long as it keeps dripping, and repeats this across streams and connections to exhaust server processes and memory.

The two paths are independent. The stream-level block is reached on its own by widening the connection window with a large WINDOW_UPDATE on stream 0 and shrinking the per-stream window with a small SETTINGS_INITIAL_WINDOW_SIZE, so closing only the connection-level path leaves it exploitable.

This issue affects bandit: from 1.4.0 before 1.13.0.

Patch / fix

  • hex bandit 1.13.0
  • mtrudel bandit 1.13.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
23 d ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/mtrudel/bandit/security/advisories/GHSA-69m6-wcv4-rwcf referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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 bandit
>=1.4.0, <1.13.0
1.13.0

Affected products

  • mtrudel bandit

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

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.