Public bug reported:
**Description**
On Ubuntu 26.04.1 LTS, `pdfsig` 26.01.0 crashes with a segmentation
fault (SIGSEGV) when validating a digitally signed PDF using the GPG
backend.
The affected PDF contains an ETSI.CAdES.detached signature and an RFC
3161 document timestamp, generated as part of a PAdES-LTA signing
workflow using pyHanko 0.38.0.
The crash appears to occur when `pdfsig` starts processing the second
signature field, which contains the document timestamp.
**Steps to reproduce**
1. Open a terminal on Ubuntu 26.04.1 LTS.
2. Use a PAdES-LTA PDF containing a digital signature and a document timestamp.
3. Execute:
`pdfsig -backend GPG document.pdf`
4. Observe that `pdfsig` crashes while processing the timestamp
signature field.
**Actual result**
The first signature is processed and reported as cryptographically
valid:
```
Signature #1:
- Signature Type: ETSI.CAdES.detached
- Signing Hash Algorithm: SHA-256
- Signature Validation: Signature is Valid.
- Certificate Validation: Certificate has not yet been verified.
Signature #2:
- Signer Certificate Common Name:
Segmentation fault (core dumped)
```
**Expected result**
`pdfsig` should validate the document timestamp if supported, or report
that it cannot be validated. It should not crash when encountering a PDF
document timestamp.
**Environment**
- Ubuntu 26.04.1 LTS (amd64)
- poppler-utils: 26.01.0-2ubuntu0.3
- libpoppler156: 26.01.0-2ubuntu0.3
- libgpgme.so.45 (GPGME 2.0.1)
- NSS: 3.120
- GPG backend selected explicitly using `-backend GPG`
**Additional information**
The crash was reproduced twice, at approximately 21:07 and 21:10 CEST on
October 23, 2026.
`coredumpctl` confirms SIGSEGV in `/usr/bin/pdfsig`. The stack trace
points to the `pdfsig` executable itself, although function symbols are
not available in the current diagnostic output.
The NSS backend does not crash on the same document. It reports the
primary signature as cryptographically valid but cannot establish
certificate validity.
The same PDF's primary digital signature was independently validated
with pyHanko 0.38.0 using the appropriate FNMT and Sectigo trust roots,
returning `VALID`.
The document contains confidential business information, so I cannot
attach the original PDF or a core dump publicly. I can provide
additional diagnostic output or help reproduce the issue using a non-
confidential sample if needed.
**Impact**
This crash prevents reliable validation of PDF documents containing
PAdES-LTA document timestamps with Poppler's GPG backend. It may also
affect applications relying on the same Poppler signature-processing
functionality.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: poppler-utils 26.01.0-2ubuntu0.3
ProcVersionSignature: Ubuntu 7.0.0-38.38-generic 7.0.14
Uname: Linux 7.0.0-38-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Oct 23 21:14:33 2026
InstallationDate: Installed on 2025-02-02 (628 days ago)
InstallationMedia: Ubuntu 24.04.1 LTS "Noble Numbat" - Release amd64
(20240827.1)
ProcEnviron:
LANG=hu_HU.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: poppler
UpgradeStatus: Upgraded to resolute on 2026-10-11 (12 days ago)
** Affects: poppler (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
--
You received this bug notification because you are a member of Ubuntu
Desktop Bugs, which is subscribed to poppler in Ubuntu.
https://bugs.launchpad.net/bugs/2172076
Title:
pdfsig 26.01.0 crashes with SIGSEGV using GPG backend on a PAdES-LTA
document timestamp
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/2172076/+subscriptions
--
desktop-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
