vulnerability / NVI-00010613 / Revision 2
Twisted: Unauthenticated Remote Denial of Service in the Twisted IRC Server via an Unbounded Line Buffer
GitHub lists this reviewed advisory for Twisted. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.501%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.42931. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
Twisted
source listed<= 26.4.0
## Summary An unbounded-buffer vulnerability (CWE-770) in the Twisted words IRC server lets any unauthenticated remote client exhaust server memory. `twisted.words.protocols.irc.IRC.dataReceived` appends every received byte to a per-connection buffer and only removes data at a line feed, with no maximum length. Because `IRC` is a plain `Protocol` and not a `LineReceiver`, one connection that streams bytes without a line feed grows the buffer without bound and drives the whole single-threaded process to out-of-memory, dropping every user at once. The `twistd words` server inherits the method unchanged through `IRCUser`, and the data is buffered before any authentication. ## Details `IRC.dataReceived` keeps everything up to the last line feed in `self.buffer`: ```python # twisted/words/protocols/irc.py class IRC(protocol.Protocol): # not a LineReceiver, so no MAX_LENGTH buffer = "" def dataReceived(self, data): if isinstance(data, bytes): data = data.decode("utf-8") lines = (self.buffer + data).split(LF) self.buffer = lines.pop() # no 3line feed -> whole input stays buffered ... ``` With no line feed in the data, `lin
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-53xc-49m8-p798 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-115776 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.