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NVD / CVE Program· CNA EEF

CVE-2026-74836: HTTP/2 connection-window starvation pins Plug processes indefinitely in Bandit

HighCVSS 8.7 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 34/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.63% (FIRST EPSS); higher than 50.9% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: mtrudel bandit 1.12.5, f6914aad14bb1365dd6f306aa592cfb0819bed3e.

Low priority for now. Upgrade to mtrudel bandit 1.12.5, f6914aad14bb1365dd6f306aa592cfb0819bed3e or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows an unauthenticated remote attacker to pin an unbounded number of HTTP/2 stream processes indefinitely via connection-level flow control. When a stream's response body outruns the HTTP/2 connection-level send window (default 65,535 bytes, shared across all streams on the connection), Bandit.HTTP2.Connection queues the remaining bytes and a reply closure in pending_sends and the stream process blocks forever inside a synchronous call to the connection process. Nothing bounds that wait and nothing purges the queue: a client RST_STREAM for the blocked stream is delivered to its mailbox but never read while it is stuck inside the call, so cancelling frees nothing, and periodic PING frames keep the transport-level read timeout from ever firing. The equivalent block on the stream-level send window is already bounded at 15 seconds; the connection-level path had no such bound. Each stalled stream pins its process, Plug state, and any resource the Plug holds across the blocked write, such as a pooled upstream connection in a reverse-proxy Plug. The attacker chooses any endpoint whose response exceeds the connection window (common for most non-trivial payloads), grants a generous stream-level window so only the connection window limits it, and keeps the connection alive with periodic PINGs; the primitive is repeatable across streams and connections at the cost of one idle socket each. This issue affects bandit: from 0.3.4 before 1.12.5.

Published
Aug 20, 2026
Updated
Oct 18, 2026
EPSS
0.6% · 50th percentile

Report tools

JSON

Action score

34

Monitor

Low priority for now.

CVSS
34 / 40 · 8.7 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · EEF
8.7
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-74836

When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (EEF). Independent of NVD's CPE analysis and usually ahead of it.

  • mtrudel bandit

    • 0.3.4 and later · before 1.12.5affected · semver
    • 6feadb31189d18b7dcda6c663112cd3bbaf63a46 and later · before f6914aad14bb1365dd6f306aa592cfb0819bed3eaffected · git

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Hexbanditfrom 0.3.4 · before 1.12.51.12.5

Same product

mtrudel: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-116078HTTP/2 request bodies made of 1-byte DATA frames amplify memory use in Bandit
    34Monitor
  • CVE-2026-115269HTTP/2 WINDOW_UPDATE and SETTINGS frames reset the request body read timeout in Bandit
    34Monitor
  • CVE-2026-114213WebSocket 1-byte continuation frames bypass `max_fragmented_message_size` in Bandit
    34Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-39806May 13, 2026 · HTTP/1 chunked decoder infinite loop on requests with trailer fields in bandit
    34Monitor
  • ← EarlierCVE-2026-65623Jul 24, 2026 · Quadratic CPU blow-up reassembling fragmented WebSocket messages in Bandit
    34Monitor
  • Later →CVE-2026-75484Aug 20, 2026 · HTTP/2 header field values containing CR, LF or NUL are passed to the application unvalidated in Bandit
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
mtrudel bandit1.12.5Vendor (CNA)
mtrudel banditf6914aad14bb1365dd6f306aa592cfb0819bed3eVendor (CNA)
Hex:bandit1.12.5Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-10852567 days apartHTTP/2 inbound flow control is not enforced, letting a client queue unbounded DATA in stream processes in Bandit
    34Monitor
  • CVE-2026-11049967 days apartClient-chosen HPACK encoder table size is applied uncapped, growing per-connection state with every response in Bandit
    34Monitor
  • CVE-2026-11110167 days apartHTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit
    34Monitor
  • CVE-2026-11421367 days apartWebSocket 1-byte continuation frames bypass `max_fragmented_message_size` in Bandit
    34Monitor
  • CVE-2026-11526967 days apartHTTP/2 WINDOW_UPDATE and SETTINGS frames reset the request body read timeout in Bandit
    34Monitor
  • CVE-2026-11607869 days apartHTTP/2 request bodies made of 1-byte DATA frames amplify memory use in Bandit
    34Monitor

Not on record for this CVE: public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-770 · Allocation of Resources Without Limits or Throttling

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records