diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9321be2..cb97d9a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -142,8 +142,10 @@
     that raw data lies inside the file without overlaps. Every problem is
     printed with its address; exit 1 when there are any. libhdf5's h5check
     reads only the 1.8 format. On the conformance corpus it passes all 418
-    files that both clawhdf5 and h5py read in full, and flags 149 of the
-    180 CVE reproducers.
+    files that both clawhdf5 and h5py read in full, and `check --data` flags
+    147 of the 180 files of the CVE corpus (tank, 2026-09-26). It inherits
+    the library's tolerance, though: 26 of the 33 it passes are files
+    h5dump 1.14.6 rejects (see `docs/known-issues.md`, header checks).
   - Values over `--max-bytes` (default 1 GiB) are reported instead of read;
     a panic is caught and reported as an internal error (exit 3).
     `scripts/h5rs-fuzz.sh` runs every subcommand over a corpus (default the
diff --git a/crates/clawhdf5-tools/README.md b/crates/clawhdf5-tools/README.md
index 342756b..d40c486 100644
--- a/crates/clawhdf5-tools/README.md
+++ b/crates/clawhdf5-tools/README.md
@@ -207,7 +207,11 @@ B-tree chunk indexes, and version 3 superblocks).
 
 What it does not check: free-space manager and shared-message (SOHM) table
 checksums, global heap collections other than those a value read touches,
-and objects reachable only by external links.
+and objects reachable only by external links. It validates with
+clawhdf5's parsers, so it accepts what they accept: some header damage that
+libhdf5 refuses goes unreported (of the 180 files of the HDF Group's CVE
+corpus, `check --data` passes 33, and h5dump 1.14.6 rejects 26 of those;
+tank, 2026-09-26).
 
 ## Robustness
 
diff --git a/docs/known-issues.md b/docs/known-issues.md
index 4ea7518..077dbfd 100644
--- a/docs/known-issues.md
+++ b/docs/known-issues.md
@@ -135,7 +135,11 @@ fill-value item that did is fixed).
 - **Filters:** blosc, blosc2, bitshuffle, bzip2, LZF and zfp are not
   implemented.
 - **Header checks:** on 12 CVE datasets libhdf5 rejects a corrupt header and
-  we read data anyway. We need stricter header checks.
+  we read data anyway. We need stricter header checks. The same gap shows in
+  `h5rs check`, which validates with the library's parsers: of the 180
+  files of the CVE corpus, `check --data` passes 33, and h5dump 1.14.6
+  rejects 26 of those (measured on tank, 2026-09-26, with
+  `h5rs check --data F` and `h5dump F` per file).
 - **Writer:**
   - Nested groups beyond one level: path-like names are now refused, not
     created.