https://db.gcve.eu Contains only the most 10 recent entries. http://www.rssboard.org/rss-specification python-feedgen en Sun, 25 Oct 2026 15:19:04 +0000 https://db.gcve.eu/vuln/fkie_cve-2026-115774 <p>Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.mail.imap4.IMAP4Server reaches twisted.mail.imap4.parseNestedParens with a negative literal size in an authenticated SEARCH command after the client enters the selected mailbox state. The negative size moves the parser cursor below zero, and Python&#39;s negative indexing prevents the synchronous scanning loop from terminating. The loop freezes the single-threaded reactor, stopping other IMAP connections and any SMTP or POP3 services hosted in the same process until restart. This issue is fixed in version 26.10.0rc1.</p> <p>Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.mail.imap4.IMAP4Server reaches twisted.mail.imap4.parseNestedParens with a negative literal size in an authenticated SEARCH command after the client enters the selected mailbox state. The negative size moves the parser cursor below zero, and Python&#39;s negative indexing prevents the synchronous scanning loop from terminating. The loop freezes the single-threaded reactor, stopping other IMAP connections and any SMTP or POP3 services hosted in the same process until restart. This issue is fixed in version 26.10.0rc1.</p> https://db.gcve.eu/vuln/fkie_cve-2026-115774 https://db.gcve.eu/vuln/ghsa-2qrf-pqgx-qh9v <p><strong>Affected:</strong> PyPI: Twisted</p> <p>## Summary</p> <p>An infinite-loop vulnerability (CWE-835) in the Twisted IMAP4 server lets an authenticated client freeze the whole process with one small command. `twisted.mail.imap4.parseNestedParens` reads an IMAP literal size with `int()` and never rejects a negative value. A negative size such as `{-100}` drives the parser cursor negative, and because a negative Python index wraps around the end of the string instead of raising, the scanning loop never terminates. It runs synchronously on the single-threaded reactor, so one `SEARCH` command holds the reactor at full CPU forever and every other connection stops being served.</p> <p>## Details</p> <p>Meeting an inline literal, `parseNestedParens` reads the size between the braces and advances the cursor past the body:</p> <p>```python # twisted/mail/imap4.py parseNestedParens literalSize = int(s[i + 1 : end]) # no sign check contentStack[-1].append((s[end + 3 : end + 3 + literalSize],)) i = end + 3 + literalSize # negative size -&gt; i goes negative ```</p> <p>`int(b&#34;-100&#34;)` is `-100`, so `i` goes negative; the loop condition `i &lt; len(s)` stays true and `s[i : i + 1]` on a negative index never raises, so the cursor cycles forever. The `_literalStringLimit` guard only covers the synchronizing-literal continuation path, not this inline branch. The call is reached from `select_SEARCH` through `arg_searchkeys`, dispatched only in the selected state, so a valid login and a selected mailbox (any low-privilege account) suffice. It…</p> <p><strong>Affected:</strong> PyPI: Twisted</p> <p>## Summary</p> <p>An infinite-loop vulnerability (CWE-835) in the Twisted IMAP4 server lets an authenticated client freeze the whole process with one small command. `twisted.mail.imap4.parseNestedParens` reads an IMAP literal size with `int()` and never rejects a negative value. A negative size such as `{-100}` drives the parser cursor negative, and because a negative Python index wraps around the end of the string instead of raising, the scanning loop never terminates. It runs synchronously on the single-threaded reactor, so one `SEARCH` command holds the reactor at full CPU forever and every other connection stops being served.</p> <p>## Details</p> <p>Meeting an inline literal, `parseNestedParens` reads the size between the braces and advances the cursor past the body:</p> <p>```python # twisted/mail/imap4.py parseNestedParens literalSize = int(s[i + 1 : end]) # no sign check contentStack[-1].append((s[end + 3 : end + 3 + literalSize],)) i = end + 3 + literalSize # negative size -&gt; i goes negative ```</p> <p>`int(b&#34;-100&#34;)` is `-100`, so `i` goes negative; the loop condition `i &lt; len(s)` stays true and `s[i : i + 1]` on a negative index never raises, so the cursor cycles forever. The `_literalStringLimit` guard only covers the synchronizing-literal continuation path, not this inline branch. The call is reached from `select_SEARCH` through `arg_searchkeys`, dispatched only in the selected state, so a valid login and a selected mailbox (any low-privilege account) suffice. It…</p> https://db.gcve.eu/vuln/ghsa-2qrf-pqgx-qh9v