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VulnerabilityPublished Updated

CVE-2025-55197: Pdfly · PyPDF's Manipulated FlateDecode streams can exhaust RAM

Affects pdflySource GCVE Database

0
Authoritative record:CVE-2025-55197· Medium 6.6

Not known to be exploited · CVSS 6.6 Medium : upgrade to 0.4.0_1 when convenient.

Data as of 26 Oct 2026, 18:58 UTC

CVSS 4.0 base score
6.6Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.4.0_1
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Aug 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade pdfly to 0.4.0_1.

Affected software

ProductAffectedFixed in
Homebrewpdflypkg:brew/pdflyOther threatsAffected
  • >=0.4.0 <0.4.0_1
Fixed in
  • 0.4.0_1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

### Impact An attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires just reading the file if a series of FlateDecode filters is used on a malicious cross-reference stream. Other content streams are affected on explicit access. ### Patches This has been fixed in [pypdf==6.0.0](https://github.com/py-pdf/pypdf/releases/tag/6.0.0). ### Workarounds If you cannot upgrade yet, you might want to implement the workaround for `pypdf.filters.decompress` yourself: https://github.com/py-pdf/pypdf/blob/0dd57738bbdcdb63f0fb43d8a6b3d222b6946595/pypdf/filters.py#L72-L143 ### References This issue has been reported in #3429 and fixed in #3430.

References

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