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idna 2.10.post1: backport CVE-2024-3651 #1

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Merged
icanhasmath merged 2 commits into from
Aug 7, 2026
Merged

idna 2.10.post1: backport CVE-2024-3651 #1

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6c269e2
Fix CVE-2024-3651: quadratic joining-type scan in idna.encode()
icanhasmath Aug 6, 2026
38cf5dc
Release 2.10.post1: idna security release
icanhasmath Aug 6, 2026
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12 changes: 12 additions & 0 deletions HISTORY.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,18 @@
History
-------

2.10.post1 (2026-08-06)
+++++++++++++++++++++++

- ActiveState security release. Fix CVE-2024-3651 (GHSA-jjg7-2v4v-x38h):
specially crafted input to idna.encode() could consume an exceptional
amount of CPU because the joining-type scan in valid_contextj() was
quadratic in the label length. Labels containing a Non_Joining codepoint
between a joiner and its context were also wrongly accepted, contrary to
RFC 5892 Appendix A.1. Backported from upstream idna 3.7; the
joining_types table is regenerated from Unicode 13.0.0
extracted/DerivedJoiningType.txt.

2.10 (2020-06-27)
+++++++++++++++++

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8 changes: 6 additions & 2 deletions idna/core.py
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Expand Up @@ -161,9 +161,11 @@ def valid_contextj(label, pos):
joining_type = idnadata.joining_types.get(ord(label[i]))
if joining_type == ord('T'):
continue
if joining_type in [ord('L'), ord('D')]:
elif joining_type in [ord('L'), ord('D')]:
ok = True
break
else:
break

if not ok:
return False
Expand All @@ -173,9 +175,11 @@ def valid_contextj(label, pos):
joining_type = idnadata.joining_types.get(ord(label[i]))
if joining_type == ord('T'):
continue
if joining_type in [ord('R'), ord('D')]:
elif joining_type in [ord('R'), ord('D')]:
ok = True
break
else:
break
return ok

if cp_value == 0x200d:
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