Py-pdf vulnerabilities

CVE-2026-57204 Medium · 6.5 CWE-400 Jun 30, 2026

pypdf: Missing stream length values ignore defined limits

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.3, a maliciously crafted PDF can cause DoS. An attacker who uses this vulnerability can craft a PDF which leads to large memory usage, as MAX_DECLARED_STREAM_LENGTH is sometimes ignored. This requires parsing a content stream without a /Length value. This issue has been fixed in version 6.13.3.

CVE-2026-54651 Medium · 5.5 CWE-835 Jun 22, 2026

pypdf: Possible infinite loop when processing threads/articles in writer

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. This vulnerability is fixed in 6.13.1.

CVE-2026-54531 Medium · 5.5 CWE-835 Jun 22, 2026

pypdf: Possible infinite loop when processing outlines/bookmarks in writer

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.0, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with outlines into a writer. This vulnerability is fixed in 6.13.0.

CVE-2026-54530 Medium · 5.5 CWE-835 Jun 22, 2026

pypdf: Possible infinite loop when retrieving fonts for layout-mode text extraction

pypdf is a free and open-source pure-python PDF library. Prior to 6.13.0, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires extracting the text in layout mode. This vulnerability is fixed in 6.13.0.

CVE-2026-49461 Medium · 5.5 CWE-400 Jun 22, 2026

pypdf: Possible large memory usage for form XObjects during text extraction

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.2, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires extracting the text of a page which contains a form XObject with self-references. This vulnerability is fixed in 6.12.2.

CVE-2026-49460 Low · 3.3 CWE-407 Jun 22, 2026

pypdf: Inefficient decoding of FlateDecode PNG predictor streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.2, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the /FlateDecode filter with a PNG predictor. This vulnerability is fixed in 6.12.2.

CVE-2026-48735 Medium · 5.5 CWE-770 May 28, 2026

pypdf: Manipulated XMP metadata streams can exhaust RAM

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.1, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing large XMP metadata, possibly with lots of unnecessary elements. This vulnerability is fixed in 6.12.1.

CVE-2026-48156 Low · 3.3 CWE-834 May 28, 2026

pypdf: Possible long runtimes for zero-only width values in cross-reference streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values. This vulnerability is fixed in 6.12.0.

CVE-2026-48155 Medium · 5.5 CWE-400 May 28, 2026

pypdf: Possible large memory usage for large offsets for layout mode text

pypdf is a free and open-source pure-python PDF library. Prior to 6.12.0, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires extracting text in layout mode with large character offsets. This vulnerability is fixed in 6.12.0.

CVE-2026-41314 Medium · 6.5 CWE-789 Apr 22, 2026

pypdf: Manipulated FlateDecode image dimensions can exhaust RAM

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.2 can craft a PDF which leads to the RAM being exhausted. This requires accessing an image using `/FlateDecode` with large size values. This has been fixed in pypdf 6.10.2. As a workaround, one may apply the changes from the patch manually.

CVE-2026-41313 Medium · 6.5 CWE-834 Apr 22, 2026

pypdf: Possible long runtimes for wrong size values in incremental mode

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.2 can craft a PDF which leads to long runtimes. This requires loading a PDF with a large trailer `/Size` value in incremental mode. This has been fixed in pypdf 6.10.2. As a workaround, one may apply the changes from the patch manually.

CVE-2026-41312 Medium · 6.5 CWE-789 Apr 22, 2026

pypdf: Manipulated FlateDecode predictor parameters can exhaust RAM

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.2 can craft a PDF which leads to the RAM being exhausted. This requires accessing a stream compressed using `/FlateDecode` with a `/Predictor` unequal 1 and large predictor parameters. This has been fixed in pypdf 6.10.2. As a workaround, one may apply the changes from the patch manually.

CVE-2026-41168 Medium · 5.3 CWE-834 Apr 22, 2026

pypdf has possible long runtimes for wrong size values in cross-reference and object streams

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.1 can craft a PDF which leads to long runtimes. This requires cross-reference streams with wrong large `/Size` values or object streams with wrong large `/N` values. This has been fixed in pypdf 6.10.1. As a workaround, one may apply the changes from the patch manually.

CVE-2026-40260 Medium · 5.3 CWE-776 Apr 16, 2026

pypdf: Manipulated XMP metadata entity declarations can exhaust RAM

pypdf is a free and open-source pure-python PDF library. In versions prior to 6.10.0, manipulated XMP metadata entity declarations can exhaust RAM. An attacker who exploits this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the XMP metadata. This issue has been fixed in version 6.10.0.

CVE-2026-33699 High · 7.5 CWE-835 Mar 26, 2026

pypdf: Possible infinite loop during recovery attempts in DictionaryObject.read_from_stream

pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.2 have a vulnerability in which an attacker can craft a PDF which leads to an infinite loop. This requires reading a file in non-strict mode. This has been fixed in pypdf 6.9.2. If users cannot upgrade yet, consider applying the changes from the patch manually.

CVE-2026-33123 Medium · 6.5 CWE-400 Mar 20, 2026

pypdf has inefficient decoding of array-based streams

pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1.

CVE-2026-31826 Medium · 5.5 CWE-770 Mar 10, 2026

pypdf: manipulated stream length values can exhaust RAM

pypdf is a free and open-source pure-python PDF library. Prior to 6.8.0, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing a content stream with a rather large /Length value, regardless of the actual data length inside the stream. This vulnerability is fixed in 6.8.0.

CVE-2026-28804 Medium · 5.3 CWE-407 Mar 6, 2026

pypdf: Inefficient decoding of ASCIIHexDecode streams

pypdf is a free and open-source pure-python PDF library. Prior to version 6.7.5, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires accessing a stream which uses the /ASCIIHexDecode filter. This issue has been patched in version 6.7.5.

CVE-2026-28351 Medium · 5.3 CWE-400 Feb 27, 2026

Manipulated RunLengthDecode streams can exhaust RAM

pypdf is a free and open-source pure-python PDF library. Prior to version 6.7.4, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the content stream using the RunLengthDecode filter. This has been fixed in pypdf 6.7.4. As a workaround, consider applying the changes from PR #3664.

CVE-2026-27888 High · 7.5 CWE-400 Feb 25, 2026

pypdf: Manipulated FlateDecode XFA streams can exhaust RAM

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.3, an attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing the `xfa` property of a reader or writer and the corresponding stream being compressed using `/FlateDecode`. This has been fixed in pypdf 6.7.3. As a workaround, apply the patch manually.

CVE-2026-27628 High · 7.5 CWE-835 Feb 25, 2026

pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.

CVE-2026-27026 Medium · 5.5 CWE-770 Feb 20, 2026

pypdf possibly has long runtimes for malformed FlateDecode streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. This vulnerability is fixed in 6.7.1.

CVE-2026-27025 Medium · 5.5 CWE-834 Feb 20, 2026

pypdf has possible long runtimes/large memory usage for large /ToUnicode streams

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes and large memory consumption. This requires parsing the /ToUnicode entry of a font with unusually large values, for example during text extraction. This vulnerability is fixed in 6.7.1.

CVE-2026-27024 Medium · 5.5 CWE-835 Feb 20, 2026

pypdf has a possible infinite loop when processing TreeObject

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires accessing the children of a TreeObject, for example as part of outlines. This vulnerability is fixed in 6.7.1.

CVE-2026-24688 Medium · 4.3 CWE-835 Jan 27, 2026

pypdf has possible Infinite Loop when processing outlines/bookmarks

pypdf is a free and open-source pure-python PDF library. An attacker who uses an infinite loop vulnerability that is present in versions prior to 6.6.2 can craft a PDF which leads to an infinite loop. This requires accessing the outlines/bookmarks. This has been fixed in pypdf 6.6.2. If projects cannot upgrade yet, consider applying the changes from PR #3610 manually.