CVE-2026-108529 json
SETTINGS and stream-0 WINDOW_UPDATE frames trigger quadratic work over blocked streams in Bandit
published 2026-10-26 13 d ago modified 2026-10-26 13 d ago also EEF-CVE-2026-108529 , GHSA-j363-h72p-296m , EUVD-2026-109829
- 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
Inefficient Algorithmic Complexity vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to exhaust server CPU via small SETTINGS or connection-level WINDOW_UPDATE frames. The attacker opens thousands of streams whose responses block on the connection send window, then sends cheap frames that each make the server walk the whole queue of blocked sends. In the reporter's run, with 3,000 blocked streams a single 9-byte SETTINGS frame took 133 ms to process.
do_pending_sends/2 in lib/bandit/http2/connection.ex retries every queued send and, before each retry, removes that entry from the queue with List.delete/2, so one frame costs O(n²) list operations for n blocked streams. max_concurrent_streams defaults to :infinity, so the attacker chooses n.
This issue affects bandit: from 0.3.4 before 1.14.0.
Patch / fix
- hex bandit 1.14.0
- mtrudel bandit 1.14.0
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 13 d ago
Exploit prediction
0.60% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).
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 | >=0.3.4, <1.14.0 |
1.14.0 |
Affected products
- mtrudel bandit
Classification
- Weakness
-
- CWE-407 Inefficient Algorithmic Complexity
References
-
github.com
/mtrudel/bandit/commit/6feadb31189d18b7dcda6c663112cd3bbaf63a46
related, web
-
github.com
/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a
patch
-
github.com
/mtrudel/bandit/security/advisories/GHSA-j363-h72p-296m
vendor-advisory, related, advisory
-
cna.erlef.org
/cves/CVE-2026-108529.html
related, web
-
osv.dev
/vulnerability/EEF-CVE-2026-108529
related
-
hex.pm
/packages/bandit
package
Sources
- CVE List CVE-2026-108529
- NVD CVE-2026-108529
- OSV EEF-CVE-2026-108529
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