hsrp, bluetooth, kerberos: fix three dissection crashes found by fuzzing - #5147
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nkbeast wants to merge 3 commits into
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hsrp, bluetooth, kerberos: fix three dissection crashes found by fuzzing#5147nkbeast wants to merge 3 commits into
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added 3 commits
September 3, 2026 02:06
HSRP.guess_payload_class read self.underlayer.len unconditionally, so dissecting an HSRP packet that carries a trailing payload without an underlayer (e.g. HSRP(b'\x00\x01' + ...) or via layers that do not expose .len) raised AttributeError instead of dissecting the trailing bytes as the default payload class. Guard the underlayer access, keeping the HSRPmd5 selection unchanged when the underlayer is present and long enough. AI-Assisted: yes (Claude)
The six FieldListField entries were given the field classes (LEMACField, ByteField, ...) instead of instances, so any dissection of the event with num_response >= 1 raised 'Field.getfield() missing 1 required positional argument'. FieldListField expects an instance per its annotation (field: AnyField). Pass instances and cover a full inquiry result round trip in the test campaign. AI-Assisted: yes (Claude)
_InitialContextTokens[_parent.TOK_ID] raised KeyError for any TOK_ID outside the implemented set, aborting the dissection of a token with an attacker-supplied or future token identifier. Fall back to conf.raw_layer, consistent with the mysummary() fallback, keeping the body as raw bytes. Known TOK_IDs are unaffected. AI-Assisted: yes (Claude)
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #5147 +/- ##
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Coverage 80.80% 80.81%
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Files 390 390
Lines 96931 96931
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+ Hits 78329 78335 +6
+ Misses 18602 18596 -6
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Three independent dissection crashes found by running random bytes through the default layers. Each commit is self-contained with its UTScapy test; no existing behavior changes.
1. hsrp
HSRP.guess_payload_classreadself.underlayer.lenunconditionally:Same class as #5089 (MQTTPublish). The HSRPmd5 selection is unchanged when the underlayer is present.
2. bluetooth
The six
FieldListFieldentries ofHCI_Event_Inquiry_Result_With_Rssiwere given field classes instead of instances, so the event could never be dissected withnum_response >= 1:Fixed by passing instances; the test campaign now round-trips a full inquiry result.
3. kerberos
KRB_InnerTokenindexed_InitialContextTokens[_parent.TOK_ID]directly, so any TOK_ID outside the implemented set aborted the dissection with aKeyError. Fall back toconf.raw_layer(consistent with the existingmysummary()fallback), keeping the body as raw bytes. Known TOK_IDs are unaffected.