File CVE-2026-23490.patch of Package python-pyasn1.42351

From 3908f144229eed4df24bd569d16e5991ace44970 Mon Sep 17 00:00:00 2001
From: Simon Pichugin <simon.pichugin@gmail.com>
Date: Fri, 16 Jan 2026 08:57:23 -0800
Subject: [PATCH] Merge commit from fork

Add limit of 20 continuation octets per OID arc to prevent a potential memory
exhaustion from excessive continuation bytes input.
---
 pyasn1/codec/ber/decoder.py     |  20 ++++-
 tests/codec/ber/test_decoder.py | 130 ++++++++++++++++++++++++++++++++
 2 files changed, 149 insertions(+), 1 deletion(-)

Index: pyasn1-0.1.9/pyasn1/codec/ber/decoder.py
===================================================================
--- pyasn1-0.1.9.orig/pyasn1/codec/ber/decoder.py
+++ pyasn1-0.1.9/pyasn1/codec/ber/decoder.py
@@ -4,6 +4,10 @@ from pyasn1.codec.ber import eoo
 from pyasn1.compat.octets import oct2int, isOctetsType
 from pyasn1 import debug, error
 
+# Maximum number of continuation octets (high-bit set) allowed per OID arc.
+# 20 octets allows up to 140-bit integers, supporting UUID-based OIDs
+MAX_OID_ARC_CONTINUATION_OCTETS = 20
+
 class AbstractDecoder:
     protoComponent = None
     def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet,
@@ -225,7 +229,14 @@ class ObjectIdentifierDecoder(AbstractSi
                 # Construct subid from a number of octets
                 nextSubId = subId
                 subId = 0
+                continuationOctetCount = 0
                 while nextSubId >= 128:
+                    continuationOctetCount += 1
+                    if continuationOctetCount > MAX_OID_ARC_CONTINUATION_OCTETS:
+                        raise error.PyAsn1Error(
+                            'OID arc exceeds maximum continuation octets limit (%d) '
+                            'at position %d' % (MAX_OID_ARC_CONTINUATION_OCTETS, index)
+                        )
                     subId = (subId << 7) + (nextSubId & 0x7F)
                     if index >= substrateLen:
                         raise error.SubstrateUnderrunError(
Index: pyasn1-0.1.9/test/codec/ber/test_decoder.py
===================================================================
--- pyasn1-0.1.9.orig/test/codec/ber/test_decoder.py
+++ pyasn1-0.1.9/test/codec/ber/test_decoder.py
@@ -1,6 +1,7 @@
 from pyasn1.type import tag, namedtype, univ, char
 from pyasn1.codec.ber import decoder, eoo
 from pyasn1.compat.octets import ints2octs, str2octs, null
+from pyasn1 import error
 from pyasn1.error import PyAsn1Error
 from sys import version_info
 if version_info[0:2] < (2, 7) or \
@@ -224,6 +225,72 @@ class ObjectIdentifierDecoderTestCase(un
             ints2octs((6,2,0x81,0x00))
         ) == ((2,48), null)
 
+    def testExcessiveContinuationOctets(self):
+        """Test that OID arcs with excessive continuation octets are rejected."""
+        # Create a payload with 25 continuation octets (exceeds 20 limit)
+        # 0x81 bytes are continuation octets, 0x01 terminates
+        malicious_payload = ints2octs([0x06, 26]) + ints2octs([0x81] * 25) + ints2octs([0x01])
+        try:
+            decoder.decode(malicious_payload)
+        except error.PyAsn1Error:
+            pass
+        else:
+            assert 0, 'Excessive continuation octets tolerated'
+
+    def testMaxAllowedContinuationOctets(self):
+        """Test that OID arcs at the maximum continuation octets limit work."""
+        # Create a payload with exactly 20 continuation octets (at limit)
+        # This should succeed
+        payload = ints2octs([0x06, 21]) + ints2octs([0x81] * 20) + ints2octs([0x01])
+        try:
+            decoder.decode(payload)
+        except error.PyAsn1Error:
+            assert 0, 'Valid OID with 20 continuation octets rejected'
+
+    def testOneOverContinuationLimit(self):
+        """Test boundary: 21 continuation octets (one over limit) is rejected."""
+        payload = ints2octs([0x06, 22]) + ints2octs([0x81] * 21) + ints2octs([0x01])
+        try:
+            decoder.decode(payload)
+        except error.PyAsn1Error:
+            pass
+        else:
+            assert 0, '21 continuation octets tolerated (should be rejected)'
+
+    def testExcessiveContinuationInSecondArc(self):
+        """Test that limit applies to subsequent arcs, not just the first."""
+        # First arc: valid simple byte (0x55 = 85, decodes to arc 2.5)
+        # Second arc: excessive continuation octets
+        payload = ints2octs([0x06, 27]) + ints2octs([0x55]) + ints2octs([0x81] * 25) + ints2octs([0x01])
+        try:
+            decoder.decode(payload)
+        except error.PyAsn1Error:
+            pass
+        else:
+            assert 0, 'Excessive continuation in second arc tolerated'
+
+    def testMultipleArcsAtLimit(self):
+        """Test multiple arcs each at the continuation limit work correctly."""
+        # Two arcs, each with 20 continuation octets (both at limit)
+        arc1 = ints2octs([0x81] * 20) + ints2octs([0x01]) # 21 bytes
+        arc2 = ints2octs([0x81] * 20) + ints2octs([0x01]) # 21 bytes
+        payload = ints2octs([0x06, 42]) + arc1 + arc2
+        try:
+            decoder.decode(payload)
+        except error.PyAsn1Error:
+            assert 0, 'Multiple valid arcs at limit rejected'
+
+    def testExcessiveContinuationWithMaxBytes(self):
+        """Test with 0xFF continuation bytes (maximum value, not just 0x81)."""
+        # 0xFF bytes are also continuation octets (high bit set)
+        malicious_payload = ints2octs([0x06, 26]) + ints2octs([0xFF] * 25) + ints2octs([0x01])
+        try:
+            decoder.decode(malicious_payload)
+        except error.PyAsn1Error:
+            pass
+        else:
+            assert 0, 'Excessive 0xFF continuation octets tolerated'
+
 
     def testEdge7(self):
         assert decoder.decode(