diff --git a/display/printf.rs b/display/printf.rs
index c9358512..20543929 100644
--- a/display/printf.rs
+++ b/display/printf.rs
@@ -840,6 +840,10 @@ fn parse_integer_arg(arg: &[u8]) -> Result<(i64, bool), String> {
         .or_else(|| num_str.strip_prefix("0X"))
     {
         // Hexadecimal
+        // Reject if hex part starts with a sign (after we already handled the sign above)
+        if hex.starts_with('+') || hex.starts_with('-') {
+            return Err(format!("invalid number: {arg_str}"));
+        }
         match i64::from_str_radix(hex, 16) {
             Ok(n) => (n, true),
             Err(_) => {
@@ -863,6 +867,10 @@ fn parse_integer_arg(arg: &[u8]) -> Result<(i64, bool), String> {
             .unwrap_or(false)
     {
         // Octal
+        // Reject if octal part starts with a sign (after we already handled the sign above)
+        if num_str.starts_with('+') || num_str.starts_with('-') {
+            return Err(format!("invalid number: {arg_str}"));
+        }
         let valid_len = num_str
             .chars()
             .take_while(|c| ('0'..='7').contains(c))
diff --git a/display/tests/printf/mod.rs b/display/tests/printf/mod.rs
index 8ef68055..f7d0df79 100644
--- a/display/tests/printf/mod.rs
+++ b/display/tests/printf/mod.rs
@@ -532,3 +532,26 @@ fn test_float_missing_arg() {
 fn test_float_char_constant() {
     printf_test(&["%f", "'A"], "65.000000");
 }
+
+// Regression tests for from_str_radix security issue
+// These should fail because double signs are invalid
+#[test]
+#[should_panic]
+fn test_reject_double_plus_hex() {
+    // This should fail: "+0x+55" should be rejected, not parsed as 0x55
+    printf_test(&["%d", "+0x+55"], "85");
+}
+
+#[test]
+#[should_panic]
+fn test_reject_double_minus_hex() {
+    // This should fail: "-0x-55" should be rejected
+    printf_test(&["%d", "-0x-55"], "-85");
+}
+
+#[test]
+#[should_panic]
+fn test_reject_double_plus_octal() {
+    // This should fail: "+0+55" should be rejected
+    printf_test(&["%d", "+0+55"], "45");
+}
diff --git a/file/find.rs b/file/find.rs
index 93fab9dd..c26eb983 100644
--- a/file/find.rs
+++ b/file/find.rs
@@ -476,12 +476,14 @@ fn parse_perm_mode(mode_str: &str) -> Result<PermMode, String> {
 
 /// Parse a mode value (octal or symbolic)
 fn parse_mode_value(mode_str: &str) -> Result<u32, String> {
-    // Try octal first
-    if let Ok(m) = u32::from_str_radix(mode_str, 8) {
-        if m > 0o7777 {
-            return Err(format!("invalid mode: {}", mode_str));
+    // Try octal first, but reject if it starts with a sign
+    if !mode_str.starts_with('+') && !mode_str.starts_with('-') {
+        if let Ok(m) = u32::from_str_radix(mode_str, 8) {
+            if m > 0o7777 {
+                return Err(format!("invalid mode: {}", mode_str));
+            }
+            return Ok(m);
         }
-        return Ok(m);
     }
 
     // Parse as symbolic mode starting from 0
diff --git a/file/od.rs b/file/od.rs
index 0e9a6406..eea1a30d 100644
--- a/file/od.rs
+++ b/file/od.rs
@@ -219,9 +219,19 @@ fn parse_count<T: FromStr<Err = ParseIntError> + FromStrRadix>(
     count: &str,
 ) -> Result<T, Box<dyn std::error::Error>> {
     if count.starts_with("0x") || count.starts_with("0X") {
-        T::from_str_radix(&count[2..], 16).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+        let hex_part = &count[2..];
+        // Reject if hex part contains a sign
+        if hex_part.starts_with('+') || hex_part.starts_with('-') {
+            return Err("invalid hexadecimal number".into());
+        }
+        T::from_str_radix(hex_part, 16).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
     } else if count.starts_with('0') && count.len() > 1 {
-        T::from_str_radix(&count[1..], 8).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+        let oct_part = &count[1..];
+        // Reject if octal part contains a sign
+        if oct_part.starts_with('+') || oct_part.starts_with('-') {
+            return Err("invalid octal number".into());
+        }
+        T::from_str_radix(oct_part, 8).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
     } else {
         count
             .parse::<T>()
@@ -279,6 +289,11 @@ fn parse_offset(offset: &str) -> Result<u64, ParseIntError> {
         offset
     };
 
+    // Reject if offset contains a sign (offsets should be unsigned)
+    if offset.starts_with('+') || offset.starts_with('-') {
+        return Err("invalid offset".parse::<u64>().unwrap_err());
+    }
+
     let parsed_offset = u64::from_str_radix(offset, base)?;
 
     Ok(parsed_offset * multiplier)
diff --git a/pax/formats/cpio.rs b/pax/formats/cpio.rs
index 181b1a7e..78752bfc 100644
--- a/pax/formats/cpio.rs
+++ b/pax/formats/cpio.rs
@@ -272,8 +272,12 @@ fn parse_header<R: Read>(header: &[u8; HEADER_SIZE], reader: &mut R) -> PaxResul
 fn parse_octal_field(bytes: &[u8]) -> PaxResult<u64> {
     let s = std::str::from_utf8(bytes)
         .map_err(|_| PaxError::InvalidHeader("invalid octal field".to_string()))?;
-    u64::from_str_radix(s.trim(), 8)
-        .map_err(|_| PaxError::InvalidHeader(format!("invalid octal: {}", s)))
+    let s = s.trim();
+    // Reject if the octal string contains a sign
+    if s.starts_with('+') || s.starts_with('-') {
+        return Err(PaxError::InvalidHeader(format!("invalid octal: {}", s)));
+    }
+    u64::from_str_radix(s, 8).map_err(|_| PaxError::InvalidHeader(format!("invalid octal: {}", s)))
 }
 
 /// Parse filename, removing NUL terminator
diff --git a/pax/formats/pax.rs b/pax/formats/pax.rs
index 8bc75aa2..1a030297 100644
--- a/pax/formats/pax.rs
+++ b/pax/formats/pax.rs
@@ -837,6 +837,10 @@ fn parse_octal(bytes: &[u8]) -> PaxResult<u64> {
     if s.is_empty() {
         return Ok(0);
     }
+    // Reject if the octal string contains a sign
+    if s.starts_with('+') || s.starts_with('-') {
+        return Err(PaxError::InvalidHeader(format!("invalid octal: {}", s)));
+    }
     u64::from_str_radix(&s, 8).map_err(|_| PaxError::InvalidHeader(format!("invalid octal: {}", s)))
 }
 
diff --git a/pax/formats/ustar.rs b/pax/formats/ustar.rs
index 84862b18..fc1add95 100644
--- a/pax/formats/ustar.rs
+++ b/pax/formats/ustar.rs
@@ -273,6 +273,10 @@ fn parse_octal(bytes: &[u8]) -> PaxResult<u64> {
     if s.is_empty() {
         return Ok(0);
     }
+    // Reject if the octal string contains a sign
+    if s.starts_with('+') || s.starts_with('-') {
+        return Err(PaxError::InvalidHeader(format!("invalid octal: {}", s)));
+    }
     u64::from_str_radix(&s, 8).map_err(|_| PaxError::InvalidHeader(format!("invalid octal: {}", s)))
 }
 
diff --git a/pax/main.rs b/pax/main.rs
index 063df8fc..69666e8c 100644
--- a/pax/main.rs
+++ b/pax/main.rs
@@ -557,6 +557,11 @@ fn is_valid_tar_checksum(buf: &[u8]) -> bool {
         return false;
     }
 
+    // Reject if checksum contains a sign
+    if chksum_str.starts_with('+') || chksum_str.starts_with('-') {
+        return false;
+    }
+
     let stored = match u32::from_str_radix(chksum_str, 8) {
         Ok(v) => v,
         Err(_) => return false,
diff --git a/pax/modes/append.rs b/pax/modes/append.rs
index 94b135e5..1687ff9a 100644
--- a/pax/modes/append.rs
+++ b/pax/modes/append.rs
@@ -124,6 +124,11 @@ fn is_valid_tar_checksum(header: &[u8]) -> bool {
         return false;
     }
 
+    // Reject if checksum contains a sign
+    if chksum_str.starts_with('+') || chksum_str.starts_with('-') {
+        return false;
+    }
+
     let stored = match u32::from_str_radix(chksum_str, 8) {
         Ok(v) => v,
         Err(_) => return false,
@@ -214,6 +219,10 @@ fn parse_octal(bytes: &[u8]) -> PaxResult<u64> {
     if s.is_empty() {
         return Ok(0);
     }
+    // Reject if the octal string contains a sign
+    if s.starts_with('+') || s.starts_with('-') {
+        return Err(PaxError::InvalidHeader(format!("invalid octal: {}", s)));
+    }
     u64::from_str_radix(s, 8).map_err(|_| PaxError::InvalidHeader(format!("invalid octal: {}", s)))
 }
 
diff --git a/pax/multivolume.rs b/pax/multivolume.rs
index 575286c8..0f66910c 100644
--- a/pax/multivolume.rs
+++ b/pax/multivolume.rs
@@ -745,6 +745,10 @@ fn parse_octal(bytes: &[u8]) -> PaxResult<u64> {
     if s.is_empty() {
         return Ok(0);
     }
+    // Reject if the octal string contains a sign
+    if s.starts_with('+') || s.starts_with('-') {
+        return Err(PaxError::InvalidHeader(format!("invalid octal: {}", s)));
+    }
     u64::from_str_radix(s, 8).map_err(|_| PaxError::InvalidHeader(format!("invalid octal: {}", s)))
 }
 
diff --git a/plib/src/modestr.rs b/plib/src/modestr.rs
index 68498c00..ab84874b 100644
--- a/plib/src/modestr.rs
+++ b/plib/src/modestr.rs
@@ -72,8 +72,11 @@ enum ParseState {
 }
 
 pub fn parse(mode: &str) -> Result<ChmodMode, String> {
-    if let Ok(m) = u32::from_str_radix(mode, 8) {
-        return Ok(ChmodMode::Absolute(m, mode.len() as u32));
+    // Try parsing as octal, but reject if it starts with a sign
+    if !mode.starts_with('+') && !mode.starts_with('-') {
+        if let Ok(m) = u32::from_str_radix(mode, 8) {
+            return Ok(ChmodMode::Absolute(m, mode.len() as u32));
+        }
     }
 
     let mut done_with_char;
diff --git a/sh/builtin/umask.rs b/sh/builtin/umask.rs
index 99ab04f7..f05a2af5 100644
--- a/sh/builtin/umask.rs
+++ b/sh/builtin/umask.rs
@@ -56,6 +56,10 @@ impl BuiltinUtility for Umask {
         } else if option_parser.next_argument() == args.len() - 1 {
             // TODO: support symbolic umask
             let new_umask = &args[option_parser.next_argument()];
+            // Reject if umask contains a sign
+            if new_umask.starts_with('+') || new_umask.starts_with('-') {
+                return Err(format!("umask: invalid mask '{new_umask}'").into());
+            }
             let new_umask = u32::from_str_radix(new_umask, 8)
                 .map_err(|_| format!("umask: invalid mask '{new_umask}'"))?;
             if new_umask > 0o777 {
diff --git a/sys/ipcrm.rs b/sys/ipcrm.rs
index 69053f56..fc08a6ae 100644
--- a/sys/ipcrm.rs
+++ b/sys/ipcrm.rs
@@ -20,6 +20,10 @@ use libc::{semctl, semget, shmctl, shmget, shmid_ds};
 /// Parse an IPC key value that may be decimal or hexadecimal (0x prefix)
 fn parse_ipc_key(s: &str) -> Result<i32, String> {
     if let Some(hex) = s.strip_prefix("0x").or_else(|| s.strip_prefix("0X")) {
+        // Reject if hex part starts with a sign
+        if hex.starts_with('+') || hex.starts_with('-') {
+            return Err("invalid hex key: unexpected sign after 0x prefix".to_string());
+        }
         u32::from_str_radix(hex, 16)
             .map(|v| v as i32)
             .map_err(|e| format!("invalid hex key: {}", e))
diff --git a/text/tr.rs b/text/tr.rs
index 86c9761d..4e8ff3fd 100644
--- a/text/tr.rs
+++ b/text/tr.rs
@@ -625,6 +625,11 @@ mod parsing {
         let char_repetition = match repeat_string.as_str() {
             "" => CharRepetition::AsManyAsNeeded,
             st => {
+                // Reject if repeat count starts with a sign
+                if st.starts_with('+') || st.starts_with('-') {
+                    return Err(format!("invalid repeat count '{st}' in [c*n] construct",));
+                }
+
                 let radix = if st.starts_with('0') {
                     // Octal
                     8_u32
diff --git a/xform/uudecode.rs b/xform/uudecode.rs
index 6d0571da..6424553f 100644
--- a/xform/uudecode.rs
+++ b/xform/uudecode.rs
@@ -59,7 +59,12 @@ impl Header {
             panic!("Invalid encoding type");
         };
 
-        let lower_perm_bits = u32::from_str_radix(split[1], 8).expect("Invalid permission value");
+        let mode_str = split[1];
+        // Reject if mode contains a sign
+        if mode_str.starts_with('+') || mode_str.starts_with('-') {
+            panic!("Invalid permission value: unexpected sign");
+        }
+        let lower_perm_bits = u32::from_str_radix(mode_str, 8).expect("Invalid permission value");
         let out = PathBuf::from(split[2]);
 
         Self {