diff --git a/changelog.md b/changelog.md
index 7743659f..4d6df2c4 100644
--- a/changelog.md
+++ b/changelog.md
@@ -11,17 +11,24 @@ For the latest version of this document, please see [https://github.com/haskell/
 
 ### 2.3.0.0 - 2026-05-21
 
-* Fix parsing of fractional numbers to reject exponents smaller than -1024.
-  This breaking change affects `FromJSON` instances of `Fixed`, `DiffTime`, and `NominalDiffTime`,
-  rejecting more inputs. Error messages for `Ratio` and integral types are also slightly different
-  due to reusing the same bounding logic.
+* Fix DoS vulnerabilities caused by parsing large numbers (advisory [HSEC-2026-0007](https://haskell.github.io/security-advisories/advisory/HSEC-2026-0007.html)). Backported to 2.2.5.1, see below.
 * Fix typo in error message: "~~Unespected~~ Unexpected control character while parsing string literal".
 * Support nothunks 0.3.
 * Unset executable permissions in some test files and remove a broken symlink.
 * In `text-iso8601-0.2.0.0`:
-    - Reject years of more than 15 digits.
     - Accept 24:00:00 time of day.
 
+### 2.2.5.1 - 2026-08-29
+
+Fix a DoS vulnerability caused by parsing large numbers (advisory [HSEC-2026-0007](https://haskell.github.io/security-advisories/advisory/HSEC-2026-0007.html)). Backported from 2.3.0.0 to ease migration.
+
+* (HSEC-2026-0007) Fix parsing of fractional numbers to reject exponents smaller than -1024.
+  This change affects `FromJSON` instances of `Fixed`, `DiffTime`, and `NominalDiffTime`,
+  rejecting more inputs. Error messages for `Ratio` and integral types are also slightly different
+  due to reusing the same bounding logic.
+* In `text-iso8601-0.1.1.2` (backported from 0.2.0.0):
+    - (HSEC-2026-0007) Reject years of more than 15 digits.
+
 ### 2.2.5.0
 
 * Support `semialign-1.4`
diff --git a/text-iso8601/changelog.md b/text-iso8601/changelog.md
index 0cda5f02..3d833603 100644
--- a/text-iso8601/changelog.md
+++ b/text-iso8601/changelog.md
@@ -1,11 +1,21 @@
 # 0.2.0.0 - 2026-05-21
 
-- Fix parsers to reject years with more than 15 digits
+- Fix a DoS vulnerability caused by parsing large numbers (advisory [HSEC-2026-0007](https://haskell.github.io/security-advisories/advisory/HSEC-2026-0007.html)). Backported to 0.1.1.2, see below.
 - Accept 24:00:00 time of day.
 
+# 0.1.1.2 - 2026-08-29 (backport from 0.2.0.0)
+
+Fix a DoS vulnerability caused by parsing large numbers (advisory [HSEC-2026-0007](https://haskell.github.io/security-advisories/advisory/HSEC-2026-0007.html)). Backported from 0.2.0.0 to ease migration.
+
+- (HSEC-2026-0007) Fix parsers to reject years with more than 15 digits
+
+# 0.1.1.1
+
+- Support GHC-9.14
+
 # 0.1.1
 
-- Support GHC-8.6.5...9.10.1
+- Support GHC-8.6.5...9.12.1
 
 # 0.1