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Fencer Vulns
medium 5.5

CVE-2021-36978 json

QPDF 9.x through 9.1.1 and 10.x through 10.0.4 has a heap-based buffer overflow in Pl_ASCII85Decoder::write (called from Pl_AES_PDF::flush…

published 2021-07-20 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-23554

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

QPDF 9.x through 9.1.1 and 10.x through 10.0.4 has a heap-based buffer overflow in Pl_ASCII85Decoder::write (called from Pl_AES_PDF::flush and Pl_AES_PDF::finish) when a certain downstream write fails.

Patch / fix

  • qpdf Debian 14, Debian 13, Debian 12 10.1.0-1

debian advisories DEBIAN-CVE-2021-36978

  • qpdf Ubuntu 18.04 LTS 8.0.2-3ubuntu0.1
  • qpdf Ubuntu 20.04 LTS 9.1.1-1ubuntu0.1
  • qpdf Ubuntu Pro 16.04 LTS 8.0.2-3~16.04.1+esm1

ubuntu advisories UBUNTU-CVE-2021-36978

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • qpdf SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +10 more 9.0.2-150200.3.3.1
  • qpdf SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +9 more 8.0.2-150000.3.5.1
  • qpdf SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES 12 SP5 +6 more 7.1.1-3.8.1

suse advisories SUSE-SU-2022:3248-1SUSE-SU-2022:2670-1SUSE-SU-2022:2669-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-36978 updated cvss 7.8

qpdf: heap-based buffer overflow in Pl_ASCII85Decoder::write() when a certain downstream write fails

  • Red Hat Enterprise Linux 7 qpdf, qpdf-libs
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 qpdf, qpdf-libs
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 9 qpdf, qpdf-libs
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

1.27% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.