ALBA-2021:0556 glibc bug fix and enhancement update
An attacker can cause slow DNS lookups and potential service degradation via transaction ID collisions in glibc's getaddrinfo function.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is ALBA-2021:0556?
ALBA-2021:0556 is a denial of service vulnerability in glibc-benchtests, published on 16 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.
Bug Fix(es) and Enhancement(s):
glibc: Transaction ID collisions cause slow DNS lookups in getaddrinfo (BZ#1904153)
glibc: memcpy calls are slower for AMD processors on AlmaLinux 8 than AlmaLinux 7 (BZ#1913750)
Which versions are affected by ALBA-2021:0556?
Linux distribution packages (4)
glibc-benchtests AlmaLinux:8 | All versions | 2.28-127.el8_3.2 |
glibc-nss-devel AlmaLinux:8 | All versions | 2.28-127.el8_3.2 |
glibc-static AlmaLinux:8 | All versions | 2.28-127.el8_3.2 |
nss_hesiod AlmaLinux:8 | All versions | 2.28-127.el8_3.2 |
How do I fix ALBA-2021:0556?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is ALBA-2021:0556 being exploited?
There is no known exploitation of ALBA-2021:0556 in the wild and no public exploit code.