diff --git a/build.gradle b/build.gradle
index 5eccd98835..81df0804cf 100644
--- a/build.gradle
+++ b/build.gradle
@@ -107,7 +107,7 @@ subprojects {
     apply plugin: 'com.adarshr.test-logger'
 
     ext {
-        bouncyCastleVersion = '1.80'
+        bouncyCastleVersion = '1.81'
         commonsCodecVersion = '1.18.0'
         commonsCompressVersion = '1.27.1'
         commonsIoVersion = '2.19.0'
diff --git a/build.xml b/build.xml
index 170d77c618..ded2149d52 100644
--- a/build.xml
+++ b/build.xml
@@ -296,11 +296,11 @@ under the License.
 
     <!-- xml signature libs - not part of the distribution -->
     <dependency prefix="dsig.xmlsec" artifact="org.apache.santuario:xmlsec:3.0.5" usage="ooxml-provided"/>
-    <dependency prefix="dsig.bouncycastle-prov" artifact="org.bouncycastle:bcprov-jdk18on:1.80" usage="ooxml-provided"/>
-    <dependency prefix="dsig.bouncycastle-pkix" artifact="org.bouncycastle:bcpkix-jdk18on:1.80" usage="ooxml-provided"/>
-    <dependency prefix="dsig.bouncycastle-util" artifact="org.bouncycastle:bcutil-jdk18on:1.80" usage="ooxml-provided"/>
+    <dependency prefix="dsig.bouncycastle-prov" artifact="org.bouncycastle:bcprov-jdk18on:1.81" usage="ooxml-provided"/>
+    <dependency prefix="dsig.bouncycastle-pkix" artifact="org.bouncycastle:bcpkix-jdk18on:1.81" usage="ooxml-provided"/>
+    <dependency prefix="dsig.bouncycastle-util" artifact="org.bouncycastle:bcutil-jdk18on:1.81" usage="ooxml-provided"/>
     <!-- only used for signing the release - not used with the ooxml signatures -->
-    <dependency prefix="dsig.bouncycastle-bcpg" artifact="org.bouncycastle:bcpg-jdk18on:1.80" usage="util"/>
+    <dependency prefix="dsig.bouncycastle-bcpg" artifact="org.bouncycastle:bcpg-jdk18on:1.81" usage="util"/>
     <dependency prefix="ooxml.test.stax2" artifact="org.codehaus.woodstox:stax2-api:4.2.1" usage="ooxml-provided"/>
 
     <!-- svg/batik/pdf libs - not part of the distribution - move batik to its own directory because of JPMS module-path issues -->
diff --git a/poi-ooxml/src/main/java/org/apache/poi/poifs/crypt/dsig/SignatureInfo.java b/poi-ooxml/src/main/java/org/apache/poi/poifs/crypt/dsig/SignatureInfo.java
index 4b487fcc9e..2e6f7aa99f 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/poifs/crypt/dsig/SignatureInfo.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/poifs/crypt/dsig/SignatureInfo.java
@@ -154,7 +154,7 @@ import org.w3c.dom.events.MutationEvent;
  * <p>To use SignatureInfo and its sibling classes, you'll need to have the following libs
  * in the classpath:</p>
  * <ul>
- * <li>BouncyCastle bcpkix and bcprov (tested against 1.80)</li>
+ * <li>BouncyCastle bcpkix and bcprov (tested against 1.81)</li>
  * <li>Apache Santuario "xmlsec" (tested against 3.0.x)</li>
  * <li>and log4j-api (tested against 2.22.x)</li>
  * </ul>