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Posted to bugs@httpd.apache.org by bu...@apache.org on 2026/02/02 08:32:59 UTC

[Bug 69943] New: mod_http2 segfaults on busy website

https://bz.apache.org/bugzilla/show_bug.cgi?id=69943

            Bug ID: 69943
           Summary: mod_http2 segfaults on busy website
           Product: Apache httpd-2
           Version: 2.4.66
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: mod_http2
          Assignee: bugs@httpd.apache.org
          Reporter: tom.cannaerts@iodigital.com
  Target Milestone: ---

We're running a high-traffic website that is experiencing issues with mod_http2
segfaulting. This causes the connection to immediately terminate, resulting in
503 of 520 (CloudFlare) errors in our upstream proxies.

[781182.197221] apache2[482804]: segfault at 7f0af04e10b8 ip 00007f0b1726ddbb
sp 00007f0a4bffeb60 error 4 in mod_http2.so[7f0b1725d000+29000] likely on CPU
19 (core 0, socket 38)
[781273.759905] apache2[485832]: segfault at 7f0b12f9d0b8 ip 00007f0b1726ddbb
sp 00007f0a64ff8b60 error 4 in mod_http2.so[7f0b1725d000+29000] likely on CPU 4
(core 0, socket 8)
[784155.750971] apache2[580639]: segfault at 7f0ad40150b8 ip 00007f0b1726ddbb
sp 00007f0ae8ff8b60 error 4 in mod_http2.so[7f0b1725d000+29000] likely on CPU 4
(core 0, socket 8)
[786188.972089] apache2[649566]: segfault at 7f0ae83e30b8 ip 00007f0b1726ddbb
sp 00007f0aeaffcb60 error 4 in mod_http2.so[7f0b1725d000+29000] likely on CPU 7
(core 0, socket 14)

It's always the same error and address / ip values. Disabling mod_http2
obviously 'fixes' the issue.

We're running:
- Debian 12
- Apache 2.4.66-1~deb12u1
- libnghttp2-14:amd64 1.52.0-1+deb12u2

This problem started showing up after we upgraded from Apache 2.4.65 to Apache
2.4.66.

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[Bug 69943] mod_http2 segfaults on busy website

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=69943

--- Comment #6 from Steffen <in...@apachelounge.com> ---
New versions of http2 (2.0.39) are available at  www.apachelounge.com

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[Bug 69943] mod_http2 segfaults on busy website

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=69943

Ruediger Pluem <rp...@apache.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |NEEDINFO

--- Comment #1 from Ruediger Pluem <rp...@apache.org> ---
This looks like PR69943. Can you try the patch from there
(https://bz.apache.org/bugzilla/show_bug.cgi?id=69899#c18)?

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[Bug 69943] mod_http2 segfaults on busy website

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=69943

--- Comment #3 from Ruediger Pluem <rp...@apache.org> ---
(In reply to Tom Cannaerts from comment #2)
> (In reply to Ruediger Pluem from comment #1)
> > This looks like PR69943. Can you try the patch from there
> > (https://bz.apache.org/bugzilla/show_bug.cgi?id=69899#c18)?
> 
> I'm using the pre-packaged Debian version which comes with mod_http2
> bundled. Is there any guidance on how I would best build and test this?  
> 
> I would also have to see if I can reproduce it on Acc, as I won't be able to
> compile or install custom packages on prod.

You could either build directly from the sources or try to adjust the Debian
source package as the reporter in
https://bz.apache.org/bugzilla/show_bug.cgi?id=69899#c18 did. I am no expert on
Debian source packages and thus cannot provide help here. Another option is to
open a bug report with Debian and ask them to add the patch from
https://bz.apache.org/bugzilla/show_bug.cgi?id=69899#c18 to their package.

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[Bug 69943] mod_http2 segfaults on busy website

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=69943

--- Comment #2 from Tom Cannaerts <to...@iodigital.com> ---
(In reply to Ruediger Pluem from comment #1)
> This looks like PR69943. Can you try the patch from there
> (https://bz.apache.org/bugzilla/show_bug.cgi?id=69899#c18)?

I'm using the pre-packaged Debian version which comes with mod_http2 bundled.
Is there any guidance on how I would best build and test this?  

I would also have to see if I can reproduce it on Acc, as I won't be able to
compile or install custom packages on prod.

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[Bug 69943] mod_http2 segfaults on busy website

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=69943

--- Comment #4 from Dan McLaughlin <da...@danshome.net> ---
We are seeing issues in Windows 2019 using the latest 2.4.66 from ApacheLounge.
 Any talk of when we might see a 2.4.67 release?  Any workarounds other than
disabling mod_http2 for now?

Server version: Apache/2.4.66 (Win64)
Apache Lounge VS18 Server built:   Jan 30 2026 15:51:08
Server's Module Magic Number: 20120211:141
Server loaded:  APR 1.7.6, APR-UTIL 1.6.3, PCRE 10.47 2025-10-21
Compiled using: APR 1.7.6, APR-UTIL 1.6.3, PCRE 10.47 2025-10-21
Architecture:   64-bit
Server MPM:     WinNT
  threaded:     yes (fixed thread count)
    forked:     no
Server compiled with....
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses disabled)
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D DYNAMIC_MODULE_LIMIT=256
 -D HTTPD_ROOT="/apache"
 -D SUEXEC_BIN="/apache/bin/suexec"
 -D DEFAULT_PIDLOG="logs/httpd.pid"
 -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
 -D DEFAULT_ERRORLOG="logs/error.log"
 -D AP_TYPES_CONFIG_FILE="conf/mime.types"
 -D SERVER_CONFIG_FILE="conf/httpd.conf"

I will see things like..

[Tue Mar 10 09:03:13.034853 2026] [http2:warn] [pid 10588:tid 568] AH10291:
h2_workers: cleanup, 4 workers (0 idle) did not exit after 5 seconds.

Apache stops accepting requests, if I look at TCP connections I see a bunch of
things stuck in close_wait, and the only logging happening is messages like
these in the error log that will happen indefinitely until I bounce apache.

[2026-03-10 09:13:13.116281] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:13:59.034628] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:14:13.119597] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:14:13.119597] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:14:59.207873] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:15:13.303407] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:15:13.303407] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:15:59.232804] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:16:13.325887] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:16:13.325887] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:16:59.250963] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:17:13.342384] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0

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[Bug 69943] mod_http2 segfaults on busy website

Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=69943

--- Comment #5 from Dan McLaughlin <da...@danshome.net> ---
We are seeing issues in Windows 2019 using the latest 2.4.66 from ApacheLounge.
 Any talk of when we might see a 2.4.67 release?  Any workarounds other than
disabling mod_http2 for now?

Server version: Apache/2.4.66 (Win64)
Apache Lounge VS18 Server built:   Jan 30 2026 15:51:08
Server's Module Magic Number: 20120211:141
Server loaded:  APR 1.7.6, APR-UTIL 1.6.3, PCRE 10.47 2025-10-21
Compiled using: APR 1.7.6, APR-UTIL 1.6.3, PCRE 10.47 2025-10-21
Architecture:   64-bit
Server MPM:     WinNT
  threaded:     yes (fixed thread count)
    forked:     no
Server compiled with....
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses disabled)
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D DYNAMIC_MODULE_LIMIT=256
 -D HTTPD_ROOT="/apache"
 -D SUEXEC_BIN="/apache/bin/suexec"
 -D DEFAULT_PIDLOG="logs/httpd.pid"
 -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
 -D DEFAULT_ERRORLOG="logs/error.log"
 -D AP_TYPES_CONFIG_FILE="conf/mime.types"
 -D SERVER_CONFIG_FILE="conf/httpd.conf"

I will see things like..

[Tue Mar 10 09:03:13.034853 2026] [http2:warn] [pid 10588:tid 568] AH10291:
h2_workers: cleanup, 4 workers (0 idle) did not exit after 5 seconds.

Apache stops accepting requests, if I look at TCP connections I see a bunch of
things stuck in close_wait, and the only logging happening is messages like
these in the error log that will happen indefinitely until I bounce apache.

[2026-03-10 09:13:13.116281] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:13:59.034628] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:14:13.119597] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:14:13.119597] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:14:59.207873] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:15:13.303407] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:15:13.303407] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:15:59.232804] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:16:13.325887] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:16:13.325887] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-15,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:16:59.250963] [http2:warn] [vhost:REDACTED_HOST] [pid:7724
tid:564] [C:B76dslVCY0w] [client:REDACTED_IP:56053] [peer:REDACTED_IP:56053]
h2_stream(7724-3414-1,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0
[2026-03-10 09:17:13.342384] [http2:warn] [vhost:REDACTED_HOST] [pid:10588
tid:568] [C:43xQ5usxj2Q] [client:REDACTED_IP:57203] [peer:REDACTED_IP:57203]
h2_stream(10588-5104-13,CLEANUP): started=1, scheduled=1, ready=0, out_buffer=0

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