CVE-2025-55197: Pdfly · PyPDF's Manipulated FlateDecode streams can exhaust RAM
Affects pdflySource GCVE Database
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
- 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:UExploitation evidence
Disclosed: evidence found.
CVE published 13 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Homebrewpdflypkg:brew/pdflyOther threats | Affected
| Fixed in
|
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
- github.com/py-pdf/pypdf/security/advisories/GHSA-7hfw-26vp-jp8m (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2025-55197 (opens in a new tab)
- github.com/py-pdf/pypdf/issues/3429 (opens in a new tab)
- github.com/py-pdf/pypdf/pull/3430 (opens in a new tab)
- github.com/py-pdf/pypdf (opens in a new tab)
- github.com/py-pdf/pypdf/blob/0dd57738bbdcdb63f0fb43d8a6b3d222b6946595/pypdf/filters.py (opens in a new tab)
- github.com/py-pdf/pypdf/releases/tag/6.0.0 (opens in a new tab)