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fix(strictKex): null check in isStrictKex #504

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Merged
kruton merged 1 commit into from
Jun 9, 2026
Merged

fix(strictKex): null check in isStrictKex #504

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10 changes: 9 additions & 1 deletion src/main/java/com/trilead/ssh2/transport/KexManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -897,7 +897,15 @@ public synchronized void handleMessage(byte[] msg, int msglen) throws IOExceptio
throw new IllegalStateException("Unkown KEX method! (" + kxs.np.kex_algo + ")");
}

/**
* Returns whether strict key exchange has been negotiated for the current exchange.
*
* @return {@code true} if strict key exchange has been negotiated, or {@code false}
* if negotiation has not completed or strict key exchange is not enabled
*/
public boolean isStrictKex() {
return kxs.np.isStrictKex;
KexState currentKex = kxs;
NegotiatedParameters negotiatedParameters = currentKex == null ? null : currentKex.np;
return negotiatedParameters != null && negotiatedParameters.isStrictKex;
}
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}
8 changes: 8 additions & 0 deletions src/test/java/com/trilead/ssh2/transport/KexManagerTest.java
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Expand Up @@ -18,6 +18,7 @@
import java.io.IOException;
import java.security.SecureRandom;

import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertThrows;

import static org.hamcrest.MatcherAssert.assertThat;
Expand Down Expand Up @@ -76,6 +77,13 @@ public void twoKEXCalls_OneOutputPacket() throws Exception {
verify(tm, times(1)).sendKexMessage(any());
}

@Test
public void strictKexBeforeNegotiation_ReturnsFalse() throws Exception {
kexManager.initiateKEX(new CryptoWishList(), new DHGexParameters());

assertFalse(kexManager.isStrictKex());
}

@Test
public void handlePacket_BeforeKex_NotKexInit_ThrowsException() throws Exception {
assertThrows(IOException.class, () -> {
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