WimHandler: backport 7-Zip 26.01 securId+1 bounds check - #261
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Upstream 7-Zip 26.01 tightened CHandler::GetSecurity() so that both securId and securId+1 are checked against image.SecurOffsets.Size() before indexing. p7zip's GetSecurity() bounds securityId against SecurOffsets.Size() but the next two lines do: UInt32 offs = image.SecurOffsets[securityId]; UInt32 len = image.SecurOffsets[securityId + 1] - offs; so the second indexing reads one element past the end of the SecurOffsets array whenever securityId == SecurOffsets.Size() - 1. A crafted WIM image with a valid-looking-but-last security id produces a 4-byte out-of-bounds read of attacker-influenced metadata during GetProperty(kpidNtSecure). Patch matches upstream 7-Zip 26.01 source. Signed-off-by: tonghuaroot <tonghuaroot@gmail.com>
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Backports the
CHandler::GetSecurity()bounds-check tightening landed in upstream 7-Zip 26.01 (released 2026-04-27).What changed upstream
26.00 / p7zip bounded
securityIdagainstimage.SecurOffsets.Size()but the very next two lines do:```cpp
UInt32 offs = image.SecurOffsets[securityId];
UInt32 len = image.SecurOffsets[securityId + 1] - offs;
```
So the second indexing reads one element past the end of the
SecurOffsetsarray wheneversecurityId == SecurOffsets.Size() - 1(the last valid index).26.01 changes the check to require both
securIdandsecurId + 1to be belowSecurOffsets.Size().Impact
A crafted WIM image with a valid-looking-but-last security id produces a 4-byte out-of-bounds read of attacker-influenced metadata during
GetProperty(kpidNtSecure). The read offset is consumed asoffsand influences subsequent*data = buf + offsexposed via the IInArchive interface; downstream consumers may see attacker-influenced data.Patch
Byte-for-byte matches upstream 26.01 source.
Disclosure
I am not a native English speaker. AI tooling was used to polish the prose in this PR description. The fix itself is a direct backport from upstream 7-Zip 26.01 source; no design choices were made beyond matching upstream verbatim.