diff -Nru gsl-2.7.1+dfsg/debian/changelog gsl-2.7.1+dfsg/debian/changelog
--- gsl-2.7.1+dfsg/debian/changelog	2023-09-12 15:47:39.000000000 +0000
+++ gsl-2.7.1+dfsg/debian/changelog	2023-09-27 13:55:43.000000000 +0000
@@ -1,3 +1,17 @@
+gsl (2.7.1+dfsg-6ubuntu1) mantic; urgency=low
+
+  * Merge from Debian unstable. Remaining changes:
+    - d/rules: Use -O2 instead of -O3 on ppc64el.
+
+ -- Gianfranco Costamagna <locutusofborg@debian.org>  Wed, 27 Sep 2023 15:55:43 +0200
+
+gsl (2.7.1+dfsg-6) unstable; urgency=medium
+
+  * debian/patches/quantiles_update_from_2.8: Patch from upstream bug
+    https://savannah.gnu.org/bugs/?59624 addressing CVE-2020-35357
+    
+ -- Dirk Eddelbuettel <edd@debian.org>  Tue, 26 Sep 2023 07:03:36 -0500
+
 gsl (2.7.1+dfsg-5ubuntu1) mantic; urgency=medium
 
   * d/rules: Use -O2 instead of -O3 on ppc64el. (LP: #2035228)
@@ -975,5 +989,3 @@
   * Remove the test-switch program
 
  -- Michael J. Booth <booth@debian.org>  Sun,  2 Aug 1998 22:56:51 -0400
-
-
diff -Nru gsl-2.7.1+dfsg/debian/patches/quantiles_update_from_2.8 gsl-2.7.1+dfsg/debian/patches/quantiles_update_from_2.8
--- gsl-2.7.1+dfsg/debian/patches/quantiles_update_from_2.8	1970-01-01 00:00:00.000000000 +0000
+++ gsl-2.7.1+dfsg/debian/patches/quantiles_update_from_2.8	2023-09-26 12:03:36.000000000 +0000
@@ -0,0 +1,88 @@
+Description: Improved upstream version of quantiles function
+ This is an upstream change in the upcoming, not-yet released GSL 2.8 which
+ addresses an issue raised in CVE-2020-35357. TODO: Put a short summary on the line above and replace this paragraph
+ with a longer explanation of this change. Complete the meta-information
+ with other relevant fields (see below for details). To make it easier, the
+ information below has been extracted from the changelog. Adjust it or drop
+ it.
+ .
+ gsl (2.7.1+dfsg-6) unstable; urgency=medium
+ .
+   * statistics/quantiles_source.c: Apply patch from upstream bug report
+     https://savannah.gnu.org/bugs/?59624 addressing CVE-2020-35357
+Author: Dirk Eddelbuettel <edd@debian.org>
+
+---
+The information above should follow the Patch Tagging Guidelines, please
+checkout https://dep.debian.net/deps/dep3/ to learn about the format. Here
+are templates for supplementary fields that you might want to add:
+
+Origin: upstream
+Bug: https://savannah.gnu.org/bugs/?59624
+Bug-Debian: https://bugs.debian.org/1052655
+Forwarded: no
+Applied-Upstream: https://git.savannah.gnu.org/cgit/gsl.git/commit/?id=989a193268b963aa1047814f7f1402084fb7d859
+Last-Update: 2023-09-26
+
+--- gsl-2.7.1+dfsg.orig/statistics/quantiles.c
++++ gsl-2.7.1+dfsg/statistics/quantiles.c
+@@ -1,5 +1,6 @@
+ #include <config.h>
+ #include <gsl/gsl_statistics.h>
++#include <gsl/gsl_errno.h>
+ 
+ #define BASE_LONG_DOUBLE
+ #include "templates_on.h"
+--- gsl-2.7.1+dfsg.orig/statistics/quantiles_source.c
++++ gsl-2.7.1+dfsg/statistics/quantiles_source.c
+@@ -17,29 +17,35 @@
+  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+  */
+ 
+-
+ double
+ FUNCTION(gsl_stats,quantile_from_sorted_data) (const BASE sorted_data[], 
+                                                const size_t stride,
+                                                const size_t n,
+                                                const double f)
+ {
+-  const double index = f * (n - 1) ;
+-  const size_t lhs = (int)index ;
+-  const double delta = index - lhs ;
+-  double result;
+-
+-  if (n == 0)
+-    return 0.0 ;
+-
+-  if (lhs == n - 1)
++  if ((f < 0.0) || (f > 1.0))
+     {
+-      result = sorted_data[lhs * stride] ;
++      GSL_ERROR_VAL ("invalid quantile fraction", GSL_EDOM, 0.0);
+     }
+-  else 
++  else
+     {
+-      result = (1 - delta) * sorted_data[lhs * stride] + delta * sorted_data[(lhs + 1) * stride] ;
+-    }
++      const double index = f * (n - 1) ;
++      const size_t lhs = (int)index ;
++      const double delta = index - lhs ;
++      double result;
+ 
+-  return result ;
++      if (n == 0)
++        return 0.0 ;
++
++      if (lhs == n - 1)
++        {
++          result = sorted_data[lhs * stride] ;
++        }
++      else
++        {
++          result = (1 - delta) * sorted_data[lhs * stride] + delta * sorted_data[(lhs + 1) * stride] ;
++        }
++
++      return result ;
++    }
+ }
diff -Nru gsl-2.7.1+dfsg/debian/patches/series gsl-2.7.1+dfsg/debian/patches/series
--- gsl-2.7.1+dfsg/debian/patches/series	2023-09-12 09:35:25.000000000 +0000
+++ gsl-2.7.1+dfsg/debian/patches/series	2023-09-26 12:03:36.000000000 +0000
@@ -5,3 +5,4 @@
 manual-page-correction
 ## renamed-delete
 ## correct-libtool-age-setting
+quantiles_update_from_2.8